A three angle valve job along w/the seat-to-bowl transition smoothing will be the bulk of the easy to do improvements. If the valves have a wide enough margin (this can be a problem when reusing old valves) you can see if they'll take a 30° back cut- this will help flow. If the valves are new there will be no problem retaining enough margin.
Using larger diameter valves than the stock 1.787" x 1.406" can be done- but if you do use larger valves from the 360 or 360 heads w/2.025" x 1.625" valves, the results may be less than expected (if they fit, period!) because of the close proximity of the valves to the 3-3/4" diameter cylinder bore. Some builders will opt for the Chevy valves (1.94" max intake, 1.55 for exhaust).
Seems the '70- '73 non bridged rocker heads are preferred. The '68-'69 exhaust ports were the rectangular-type and used different diameter head bolts. Heads newer than '73 had paired rockers.
Last edited by cobalt327; 04-22-2011 at 02:21 PM.