those heads are procomp brand which are made in CHINA, they are loose copies of edelbrock vic jr heads, its hit and miss with those heads, yes they will blow the doors off your stock heads in performance BUT, there can be problems with casting shift,uneven surfaces, valve guides etc.... I have know guys who had them work perfectly and others who had majore engine damage occur because of them. Best bet if you want those heads, buy them bare take them to a competent machine shop and have them assembled with quality parts OR find some used edelbrock, trick flow, AFR or even ford gt 40x or similar aluminum heads, for about a grand you can buy brand new twisted wedge or edelbrock performers or e street heads, with any of them you will have to buy new rockers and pushrods, for a cheap alternative the old cast iron gt-40 or windsor/jr heads can be found for a good deal, if you go with the aluminum heads you can run your flat top pistons and have many more cam choices and get that "lope" and the performance that goes with it you can run up to 11.1 compression with the right cam on pump gas with alum heads no problem.
your cheapest alternative is run gt-40, gt-40p (requires special headers), windsor cast iron heads, the 268h cam and 9.1 compression (Dished) stock rockers and even if you dip to 8.8 compression you can degree the cam or run more timing to make up for it.
I'll tell you, I had a 69 351w, 351w ported 69 heads (heavy bowl work) with guideplates, screw in studs and chevy 1.94 and 1.60 valves. 9.1 compression, 268h cam, 1 5/8 headers, 2 1/4 exhaust, performer intake that I port matched and a 1" spacer, a 670cfm old analog holley projection 2 TBI.
This was in my 67 vert with a c-4, 289 converter and 3.00 gears, I ran mid/high 13's in the 1/4 mile, 0-60 in 5 secs and 19 mpgs hwy. The combo had so much low end it would fry the tires, not much pull past 5000-5500 but it got there real quick and in closed loop it would have a mild lope as well as is did with a carb, I have a 500hp 408 in the car now with a lentech AOD but back then I could hit almost 80mph in first gear, peg the speedo in second and have a bit more in third. The comp cams 268h was and still is a great cam with the right combo, with better heads and compression you can do much better. But that combo worked great back then, I used to race my buddy in his 64 chevy 2 with a 383 stroker, cam and TPI and 3:73 rear gears and I would always beat him by 1/2 a car length at 120 mph.
He would always be so pissed because he head more cubes,gears and lighter he always thought I had hidden N20, a good properly matched 351w will always beat a cheby.
your cheapest alternative is run gt-40, gt-40p (requires special headers), windsor cast iron heads, the 268h cam and 9.1 compression (Dished) stock rockers and even if you dip to 8.8 compression you can degree the cam or run more timing to make up for it.
I'll tell you, I had a 69 351w, 351w ported 69 heads (heavy bowl work) with guideplates, screw in studs and chevy 1.94 and 1.60 valves. 9.1 compression, 268h cam, 1 5/8 headers, 2 1/4 exhaust, performer intake that I port matched and a 1" spacer, a 670cfm old analog holley projection 2 TBI.
This was in my 67 vert with a c-4, 289 converter and 3.00 gears, I ran mid/high 13's in the 1/4 mile, 0-60 in 5 secs and 19 mpgs hwy. The combo had so much low end it would fry the tires, not much pull past 5000-5500 but it got there real quick and in closed loop it would have a mild lope as well as is did with a carb, I have a 500hp 408 in the car now with a lentech AOD but back then I could hit almost 80mph in first gear, peg the speedo in second and have a bit more in third. The comp cams 268h was and still is a great cam with the right combo, with better heads and compression you can do much better. But that combo worked great back then, I used to race my buddy in his 64 chevy 2 with a 383 stroker, cam and TPI and 3:73 rear gears and I would always beat him by 1/2 a car length at 120 mph.
He would always be so pissed because he head more cubes,gears and lighter he always thought I had hidden N20, a good properly matched 351w will always beat a cheby.