hmm...if the engine is currently a good runner, I'd be tempted to pick up another to build, so the car isn't down as long....

personally, I'd start with an '85-up 318 or '89 up 360....why? factory roller cam. you can either use any aftermarket hydraulic roller cam with the stock lifters, or get the stock roller cam reground.

my combo, which pushes my 3900 lb 5th ave with athorita':

stock '86 long block, pistons .055 in the hole
MR. gasket .028" thick head gaskets
OEM magnum heads home ported by me.
stock magnum pushrods, rockers, lifters
stock '86 roller cam reground by www.bulletcams.com with their HR259/316 lobe both intake and exhaust
headers
eddie RPM air gap, eddie 1406 carb

don't have any times or anything, but compared to the former 360, it should be a solid mid 14 second quarter....not bad for a car that is 4100 lbs + with me in it and 3.55 rear.

if you plan on using the original short block, I'd just use enginequest 318B heads (hughes sells them for $700/pr), lunati voodoo 60400 or 60401 cam, stock magnum rockers, and an eddie RPM or LD340 intake (looks more stock than an air gap). I'd definitely run headers, they'll give you about 20hp/20 lb-ft of torque over manifolds.