The 346 has the same basic intake port as the 452 , flat floor with no short turn.

Greg you are in Rochester NY, contact Dwayne Porter, member fast68plymouth 802 951 1955, he's in Burlington VT. He'll take care of you , best money you'll spend and he may even have a set already to go. Don't waste your time and money on the Aeroheads , you'll just end up with nothing more than a stock rebuild you could get at the local autopart/machine shop for 275 bucks ...