Its not hard to get 300 hp from an amc 360. You dont necesarily need the 'oil mod'. The oil mod, in the valley, you drill/tap into the oil pump gulley and run a line to feed additional oil to the rear mains. This is only effective on cold starts and at high rpms, not needed for rockcrawling. Unless you drop some serious coin to run high rpms, you dont need the oil mod. The best oil mod you can do for a 360 is drill out the mains. The next oil concern would be your oil filter adaptor - the adaptor is the bolt-on part that your oil filter screws on to. Take your oil filter off, and look at the base of the filter adaptor, next to the threaded body should only be one hole for the oil return if your lucky. If your unlucky youll have another hole for an oil return bypass. That bypass causes erratic oil pressure and cavitation which is known to toss a rod or two or if your lucky will just blow the oil filter cap off. And of course, run a good deep sump oil pan and pickup.
With that, a 360 is an expensive bitch to build - trust me on that. Factory cast pistons are fine just thirty over or whatever overbore you can go, close out the quench and have the block 0 decked and mill the heads down to bump up compression to get you in the lower mid 9s. You can also run a ROL performance head gasket which is .039 compared to the felpro .045 which will raise compression a hair. I find a mid 70s head with the dogleg exhaust ports flow pretty well. Dont need to go overboard on head porting for offroading, just do the normal valve grinds and gasket port the exhaust which is normally 1.88x1.88 for a performance exhaust gasket. Another hp increaser but not so cheap trick, run a 1.7 roller rocker and a chevy +100 pushrod - performance increaser but not a cheap one, the machine shop will have to grind the bosses and drill and tap 7/16 for guideplates. The summit 8600 cam is a great torque cam for a budget, or isky makes a really good grunt cam but is fairly expensive. Do a low rise dual plane intake, a holley 670 w/ vacuum secondary. Double roller timing chain, etc, etc. Toss on a set of 1.75" primary headers and a 2.5" two into 1 exhaust. With the above, you will be in the mid 300s. There are other tips/tricks, the above are some basics to get you going.
