As a followup, I got the new stereo and powered sub installed. Considered all the various Westy cabinets as locations for the sub, and ultimately decided that under the bench seat facing rearwards would be the best location. Routed power to the sub directly from the main battery on a fused line, and bundled all that with the leads and controls to the sub underneath the center of the van.

The Alpine head unit fits snugly, once I bent the security retaining bracket on the dash out of the way.

After a fair bit of consideration, I decided to wire the switched power on the head to the G5 connector on the back of the fuse panel. I opted not to do the "key in" solution that Roland mentioned as I frequently leave the keys in the ignition when camping so that I don't lose them, and I don't want to run the battery down. Also, I don't generally listen to the radio when we're stopped with the engine off.

Cosmetically I decided that the Alpine unit (BT133) was one of the better looking radios out there.  Once I used some 0000 steel wool to remove some of the chrome accent striping, it felt even a bit more correct to the Vanagon styling.

It sounds good so far, and even though I haven't taken it on a road test yet, I expect that it'll make things sound a bit less muddy once the new engine installed.

-Jarrett
89 Westy