400+ HP 360 Build

Most 360's are relatively low compression 8.5:1 and for a performance build you really want a bit more. The easiest way to boost compression is to swap out the factory dished pistons for something that generates more compression, however piston choice is a bit limited for AMC engines. It's pretty hard to go past a set of Wiseco forged pistons which offer either a smaller dish for a little bit more compression or a flat top for a lot more compression. The biggest downside with these pistons is that they are only available in +0.030" and +0.045", which may not suit your particular build. You also have the option of 343 flat top pistons, which is one of the oldest AMC hot rodding tips in the book, but that are only available cast and not really that much cheaper than the Wiseco forged pistons.

Heads, I'd say that the factory heads are almost capable of supporting 450 HP without being touched, but a good valve job and some mild port work will certainly help your cause. Edelbrock heads are a good way to get something equivalent to a mildly ported factory head and are a great option if you don't have a good set of factory heads to start with. There are plenty of other advantages to the alloy head as well if they are within you budget.

Cam basically needs to be matched to the rest of the combo to achieve your goals, probably best to seek expert advice here.

I think the Air Gap and Torker are both good for 450 HP, Air Gap will be a little better at low RPM and the Torker will be a little better at high RPM.

It goes without saying that you will need a decent exhaust and the right carby to get there.

If you want to use pump gas then 10.5:1 to 11.0:1 would be your maximum compression - but maybe others that can get more. 10.5:1 would be quite street-able.

Now after you find the compression that pump gas can achieve you look at the pulse or heart beat - cam. On pump gas near 0.0520" and 108 to 110 duration seem to be the option most are happy with. More lift would be dual springs, Edy heads ... that should not be not required to get 450 HP.

The block will take the HP but you will need the pistons to get the compression and then everything else should fall into place.

Once the compression and cam are chosen then Carb/EFI and exhaust.

Headers add 20 HP over ported/cleaned cast free flows from what I've read. Too big on the headers may actually loose HP. 1-5/8" or 1-3/4" should be very close. Dual 3" H pipe to muffler and 2.5 " from there back should be close.

RPM dictates air gap - lower vs torquer -higher. 450 HP the torquer seems the choice with pump gas. It will not idle nice but sounds better then the factory radio. 

Don't undersized the carburetor -  650 Holley should be in the ball park.

Take a look at some Jeep sites and 360 builds, they spec out everything for 450 HP.