Quote:

How can I check the condition of the muffler? I put my hand over the tail pipe with the engine idling yesterday and it sure seemed like it was moving a good amount of air.
The muffler and tail pipe have been changed at some point in the car's life prior to my owning it.



Try holding your hand over the tail pipe while someone in the car revs the engine up. Should get a nice increase in volume if it's not clogged. Of course you could just cut the muffler off and see if it runs any better.

Quote:

As far as the 318, I was planning on port matching the heads and intake manifold, along with smoothing (not porting) the intake and exhaust ports, then smoothing the exhaust manifolds as much as possible and going with dual 2 1/4" exhaust.



Hmmmm, other than dual exhaust, I don't see these mods doing much for an otherwise stock 318.

Quote:

I've been looking at Super Six parts and they seem to be more expensive than a good used 318.



Yeah, costs about as much to hop up a slant 6 as it does a 318, and at the same level of mods, the 318 would make more power. V-8 swap would still be more expensive (and time-consuming) because you'll have issues other than just the engine/tranny - lot of little things, exhaust, radiator, k-frame, center link, throttle and kickdown linkage, etc. etc. And if you upgrade the 318 to make much more power than stock, then you are looking at a rear end swap, plus upgraded suspension/brakes etc.

I converted my 67 Barracuda from Slant 6 to 360, so I'm not wedded to keeping a slant; just want to give you a heads up about what you would be getting into.