What to do with my 360 magnum??

I wound up using the LA accessory setup on my Magnum but wish I just kept the serpentine. I think it's a worthwhile upgrade unless you prefer the old style look of the v rib belts. An electric fuel pump is better anyway imo, if only for the fact you don't have to crank the motor over and wait for the pump to fill the bowls. Just turn the key, wait a few seconds, and fire it up.

As for the flexplate issue, yes just enlongate one of the holes. It's been done by many with no problems, myslef included when I ran a 904. Just use some red loctite for extra insurance. B&M no longer makes then flexplatemto run a 904 behind a magnum, but sometimes you can get lucky and find one in the for sale section here.

I'd personally leave the heads alone, other than possibly cutting the valve guides to allow more cam lift. If you don't want to mess with that Hughes sells retainers that basically do the same thing. It just depends on what cam you get.