Gas gussler Van update

Good progress!

An offy intake is a considerably better idea (keeps intake heat, which is an extremely good idea for mileage and driveability—yes, even if you live someplace warm).

Comp's Slant-6 cams are junk. Not only bad blanks that shred oil pump drive gears (kerFLUSH goes the motor) but also inferior Chevy lobes that throw away the benefit of the larger-diameter Mopar lifters. Get a reground cam № 2106R from Oregon Cam. That's Doug Dutra's RV10RDP cam, torque monster with very good economy and driveability, and without making new problems.

Headers are several different kinds of non-optimal/pain in the nuts on a Slant-6 especially if you're trying for good mileage and driveability; for a street driver you're far ahead with Dutra Duals instead. Rest of the exhaust system, read this post except use this muffler (Hemi Ram item, terrific flow without drone/buzz to drive you nuts on the highway).

It is very much worth your while to get the good gaskets for the manifolds-to-head and intake-to-exhaust junctions.

Pertronix is better than points, for sure, but HEI upgrade is much better still. If nothing else, make sure your vacuum and centrifugal advance mechanisms are both working in your distributor.

Don't just guess at how much to mill off the head—Slant heads vary enough that it's too easy to eff it up and do less or more than optimal. if you're going to mill at all, find out your combustion chamber volume, decide what head gasket you'll use, and calculate how much to mill. Be aware that if you put a nice, fresh head on a well-used block, you'll be back in it to do the bottom end sooner than later (increased suction/pressure from the good-sealing head finishes off marginal rings).