Installing a 4bbl on a 273 advice

It's been a long time since I saw a LD340 so I can't say how closely the intake ports line up with the heads on a 273 which is a pretty small port
The OP said he is using a LD4B, which is a 273/318 port exit sized manifold. They’re supposed to be one of the best small port manifolds that has ever been made. The Weiand Stealth is a nearly direct copy, but has been reported to have inconsistent casting quality.