The Weiand Stealth/Action Plus intakes are essentially LD4B intakes. Still available new and show up in the for sale section occasionally.

Ports are horribly cast (I'd bet the LD4B was too), but on the one I gasket matched 6 out of 8 were 318 sized, the other two were very close to 340/360 sized already. Aside from that, darn good intakes, and a big step up from the performer which is essential an aluminum version of the late model factory four barrel, from what I can see.