Got me a set of the MP Magnum Conversion Pushrods, P5007477 (7.625) to use on my stock '88 Gran Fury Copcar factory 4bbl 318. Plan to use a stock replacement 340 cam w/ flat hydraulic lifters and stock magnum heads. What cylinder head gasket should I use? The one for the Magnum or a stock LA gasket? Anyone use these pushrods?

head gaskets are interchangeable between the LA and magnum...pick the one best suits your needs..

I used the gaskets that came in the set for the LA 318....I also used the valve cover gaskets and the LA valve covers. Keep in mind that the intake bolts on differently, though...

use the thin (.028" thick) Mr. Gasket head gasket for compression. with a '85-up shortblock and mag heads, you'll get an honest 9:1

is your copcar a 2bbl or 4bbl? 2bbl, it'll have a roller cam if it's a 2bbl...in that case, just get that cam regound by bullet cams.

if it is a flat tappet, you could buy a roller cam and use used OEM magnum pushrods, lifters, and lifter retention parts

if you're intent on sticking with a flat tappet, I'd use a lunati voodoo 60400 or 60401 instead of the 340 cam. I'll probably idle better and make more HP and torque