Build options? Couple choices - very flexible.

[Mack]

I would say get a hold of an 81 to 84 maxima head. It has the smaller intake valves, but larger exhaust valves. The smaller intakes help with port velocity, thus increasing low end grunt. It also helps that the N47 head from the maximas has the same combustion chamber shape as the P79/P90, but the volume is only 39CC, so with an F54 flat top block, and a felpro, you get an instant 11.7:1 compression ratio. Its a little much for street use, but tunable with a nice EMS, like megasquirt!

 

I have this head on an F54 non turbo block with a fel-pro head gasket and I'm running a 280ZX non EGR intake manifold that has had some work done to it. The big differences were the 60MM TB from a 240sx, and I also took all the inejector screw bumps out of the end of the runners. I also port matched the gasket to the head and did the same with the intake. ALthough the ports on the head are about 5mm bigger in diameter than the ports on the intake manifold, there were some spots that they did not line up properly and I fixed that with a dremel. I also ran a 260Z "C" stamp cam that is 256* from the factory (vs. all of the others at 240 or 248) and I am running megasquirt. the whole thing is backed by a 240sx transmission and a 3.9 LSD that I made using an infiniti M30 R200 and a z31 turbo rear. and its all running through a 2.5" mandrel bent where-the-cat-should-be back exhaust with a magnaflow 2.5" straight through muffler

 

All of this made quite the difference, taking my 1980 280ZX 2+2 from a high 17/low 18sec car in stock form, to a low low 15 second car. 0 to 60 is somewhere in the low 7s, and I still get about 30mpg on the highway. I don't know if this set uyp could be replicated or improved with carbs, but I am in the porcess of installing a regrind from colt cams as well as a custom 40mm ITB intake manifold with 40mm runners and a nice header with I feel that with this set up I should break the 200rwhp barrier. I dyno'd once before megasquirt with a faulty e12-80 dist module, it wouldn't rev past about 4200rpm, but it got up to 141rwhp and looked to be still climbing.

 

sorry for the novel, but thats my experience with all this block and head swapping mumbo jumbo.

[hartsel]

so you left the stock valves be? assuming you did, how and where could a person get ahold of a set of oversized intake valves for this head. and would that mod be worth the cost.

[Gollum]

Kind of on the back of what Mack had to share, I'd make this a really black and white answer (which is very abnormal for me) and say just run the highest compression combo you can with what you have. Then just cam appropriately. If you're not looking for the absolute most power everywhere (which you seem not to be) and just want to throw something together then it shouldn't be that hard. From what I can tell, the E31 head, on a L28 rotating assembly with flat top pistons should be over 10:1 compression. Match that with a loppy cam (which is half the run anyways right?) and voila, you have a fun street motor that'll sound mean and go quite a bit better than stock.

 

The key then to getting 150whp or 250whp will be a completely different topic which doesn't seem to be on topic in this thread. That's why my answer is kinda black and white. You want a fun street motor? Compression and cam. Looks like the only part you need to buy other than rebuild necessities would be a cam. Simple call to isky solves that...

 

Then if you want you can mess around with cleaning up the cambers, port matching, carb tuning tuning and tuning, etc. My bet is that as long as something wasn't done catastrophically wrong then you'll be very happy right out of the box.