I bought a streetrod with a Gen V 454. Was told it was a 300hp crate engine. The casting # is 12550313
I want to install a comp Thumpr cam: 279 TH 7 grind
so that I have a lopey idle. This cam was recommended by the folks at Comp Cams for what I was looking for.

According to what I read, this engine has non-adjustable rockers.

1. If I put this cam in, do I adjust the rocker nut down and that's it?
I'm concerned about proper lash with the newer higher lift (Just under 500)

2. Never having done a cam in the car, can I just cut the front oil pan gasket to remove the timing chain cover and then fill the void with RTV when I put the timing cover back on?

Any advise would be appreciated. My car is a 1930 5 window coupe.

Thanks, Upolka2