a performer intake is = to any early/mid 80s cast iron stock sperdbore intake only lighter. (there are stock sqaurebore intakes for 340/SB also)

a holley street or strip dominator intake works well and has the spredbore carb flange. work rather well for a single plan low rise intake on the street.

they LD340 and LD4B are right in the #s as the newer airgap rpm intakes,i have used a squarebore to spredbore open adaptor many times on the street with good results,not the best combo but works for street duty on these squarebore intakes.

those intakes can be hogged out to fit a spedbore intake also.

IMHO, any stock cast iron intake will fit the bill and do rather well for performance,the LD and rpm are the big step up in performance for the SB.

edelbrock made the rpm/airgap to match those alum heads and would be the best overall intake to run with them IMO.

I would even run the edelbrock cam thats matched for those heads and airgap intake for the complete power package.