will 360 j heads fit on my 273

KrazyKuda;

It is the LD340 manifold made for the smaller ports.

Click to expand...

Mistakes made. I think your fingers got confused.
The LD4B hs the smaller ports, the LD340 has the larger ports.
The Weiand Stealth has a RPM range of 1500 - 6500
Weiands Action plus is idle to 5500 i think.