When starting on a tune like this, I always start with a bone stock bin for the engine, or similar engine (when using a Delco on a non GM engine, or swapping ECMs between applications).

In most cases a stock bin will allow even some of the most modified engines start and run, and from there you can start tuning idle. then work your way up.

By far the hardest part to tune on any engine will be the cold start and cold run parameters, but with some care and being observant of actual fuel ratio, not just what the WBO2 gauge on your dash is telling you, you can at least get the engine to start and up to operating temp where the real tuning can begin. By real AFR I mean using your nose, eyes and touch to smell see and feel that the exhaust is either too lean or more commonly too rich after a rebuild. The reason for being too rich is because larger camshafts tend to produce less vacuum and therefore an ECM will think the engine is under more load than it really is, adding more fuel.

On fresh starts, I will, just to get the engine up to operating temp, using the injector scaler(s) (BPW, BPW vs EGR, etc) to lean out or richen the mixture using an emulator to keep the AFR is a close approximation of where it needs to be. Once warmed up. I will then find the sweet spot for the BPW, where the engine runs close to stoich without surging or stalling and start to adjust the VE table from there. Initial tunes take several attempts on the more modified engines. It will be a back and forth with adjustments, especially if you find you need some really high values in the VE table that do not allow for much overhead at the higher loads. I like to keep max VE in the VE table below 90%, to allow for any additional adjustments that may be needed later. The flip side is also true, if you need to reduce the values in the VE table so much that you're getting below about 20, then you may need to adjust the BPW/injector scaler. This is what I have found for the more wildly built engines.

Engines with mild modifications, such as an "EFI friendly" cam, some mild porting, headers, exhaust and maybe an intake tend to not be as much trouble. Using a stock bin has worked to get an engine running and up to temp in these situations without much issue, unless there is a mechanical issue (I'll get to that in a minute). Letting an engine warm up while being slightly rich is not the end of the world. I try to keep the warm up AFRs under 13:1, just to make sure that the oil won't be getting saturated with fuel, but this will usually allow for a smoother running engine when first tuning. The closer the AFR is to between 14.1:1 to 14.7:1 the better, but this may not happen until after the operating temp running tuning has begun or has been just about finished.

Just as an FYI, on my Nissan 2.8L I6 using code59, I started with a "stock starter bin (V4)", and had the engine running in a few minutes after making a couple starting fuel settings, but was running within a few minutes. I pulled the car on the road and after making a few VE table adjustments to get rid of a part throttle surge I was driving around in a car that was not supposed to run according to some "experts". ;)

So basically, start with a stock bin and you might be surprised just how close it will be to start tuning from. ;)

About those mechanical issues...

I had this trick me recently. A friend of mine recently upgraded the engine in his girlfriend's car, with a new cam, headers, 3" exhaust, ported heads, and maybe a couple other things that I don't recall right now. Anyway, we went out Saturday afternoon (a week ago), did some tuning on it, the WBO2 was kinda all over the place, and something didn't feel right. I couldn't nail the tune down, because what worked one minute didn't work teh next, and so I got into a sort of tuning circle. I kept mentioning how it seemed like there was a dead cylinder, or at least a very weak one. Lean spikes on the WBO2 that seemed almost cyclic screamed this to me. Anyway. We get back and the exhaust sounds different on each side of the car (true duals, no crossover). I suggest that he check the plugs and the cylinders when he got a chance and see if he finds anything. Sure enough, cyl #5 has issues. He fixes that, then the tune is way out. We went out last night, and I tuned the car all over again, and it's a whole different animal now. So make sure that what you are tuning has no mechanical issues. Even a new build does not guarantee that the engine is perfect. ;)