The biggest improvement in the cooling was moving the tell-tale outlet to the top of the block rather than the side. It allowed steam a place to escape. Always use a 6 blade impeller rather than the 3 blade that is available. Cooling is one of the advantages of the permanent cast block. The sleeves have 360 degree support by aluminum which dissipates heat much better than having a void behind the boost port with the lost foam cast.
Any of the "no choke" carbs with a 1 1/2" opening and a 1 !/4" venturi work well. I've tested all the different versions of these carbs and never found a difference in performance with any of them.
Of course these are my opinions and I'm sure you know about opinions!!!
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