Technical Performance suggestions, including carb choice?

3998993 seems like a possibility. I'll need to pull a cover and get more light on it when it cools off a bit.

 

Heads on the shelf are World Products Sportsman II angled plug 200cc runners.

 

Confirmed GM heads 3998993

1968-1976
350
1.72 intake
1.5 exhaust
Truck

 

Rear end was difficult as both wheels rotate independently of each other, but with two people turning the wheels, the driveshaft comes up just shy of 4 turns.

 

Just for reference the h312 is casting day, letter = the month, Halloween 1972?

3.73 or so gears is good news.

Back to the distributor, when you pull the cap, there should be a couple of flat plates, with springs attached, these plates and springs bring in the mechanical advance as the distibutor turns. The HEI advance kit has new springs, and /or new plates to change the mechanical advance curve.

 

Those Sportsman II's are a substantial upgrade to your stocker truck heads... They'd go great with the rpm intake and a mild performance street cam. 2.02/1.60 valves offer way more breathing than what is on there now. Also have a smaller chamber so your compression is going to go up nearly a full point. Premium fuel may be a requisite with them.
All that adds up to a significant increase in power potential of that sbc.

 

The Rockers on those heads are Harland Sharp 1.6 rollers.

 

Rear end appears to have a 3.90 or 3.91 gear ratio.
Best I can identify housing seems to match GM 10 bolt 7.5.

 

In case anyone wondered what the car looks like...

 

I suppose new heads require I ask the question again....but in addition to the 600cfm vacuum secondary and the 600cfm double pumper, I now also have a huge [rare?] Holley 650cfm spread bore carburetor (list-6512).
Do I still stick with the vacuum 600 with these new heads and rockers?

I'm also pulling the HEI and replacing with Mallory Comp 9000 (unilite), MSD Blaster 2, and Mallory Hyfire.

 

I decide to ditch both Holleys and went with a 625cfm Demon.