a y8 with a z6 head will be good for boost it will have a nice low compression....the main diff in the y8 head is the smaller quench area in the combustion chamber (less detonation). not really worth it since the z6 flows better, although the y8 intake mani is better... tha a6 pistons will be too high compression. stick with what you said at the top and youll do fine boosted...use your hf harness and wire in vtec and get a conversion harness and run obd1 for tuning purposes.