[PONTIAC LARRY]

You can use the original heads if you just get the regular 8 valve relief style replacement style std 400 pistons . The extra valve reliefs are for the use of 389 or 400 heads on a 400 and will also lower the compression into the mid 9.5:1 range maybe lower. Don't use a XE Compcam , they suck. Too much cylinder pressure (detonation) and short power band and noisy Iv'e heard. The factory 067 grind would be best in such a heavy ride. Dont be scared of inexpensive ,cast pistons.. it will still be a Super unleaded fuel engine , but with reasonable timing you should not have any problems assuming you use a 160 or 180 degree thermostat. This is also the least expensive way to build that engine too.. 389 pistons are high !