LT1 aluminum heads swap

[Fast355]

'Have to be' is a strong phrase.
If you use the aluminum heads and cam, you'd be better off using the '95 F- or Y-car spark tables.

If I were not going to port the heads, I'd use the iron heads, as they flow a lil bit better than the aluminum heads.
Aluminum heads are much easier to port, however.

Sell the iron heads on the Impala SS Forum, someone will be grateful.

The added compression of the aluminum heads more than make up for the slightly less flow. That being said the F/Y-car timing tables are not a good bet for 1,000+ lbs more car. The car will always be under more load and detonation will be likely with all the timing. He would be better adding small incremental amounts to the B-car tables. The F/Y car VE tables should be a better starting point though.