FINALLY got the rats nest of temporary wires sorted out after installing a B20 with overdrive in place on a B18/BW35 automatic combination. Took me about 7 months but I finally got to it.

I wanted to mount all the relays in a common location and make it look presentable. Ford used these great little relay blocks underhood of a lot of cars in the 90's. They are easy to re-pin, hide all the connections with a removable cover on the bottom, accept standard relay configurations, and have a nice compact footprint. I just searched a junkyard looking for one that would fit my needs. There is a little 5 or 6 fuse block that will clip right onto the side as well.

In any case, the big blue relay is the 240 sequencing overdrive relay. One small black micro relay is handling the signal to activate the overdrive from the indicator stalk "pull" function. The other is handling the reverse lights. Still got 3 open positions for future use, likely an electronic fan and maybe a headlight upgrade.

The overdrive relay is so dang tall I can't get the cover back on. Might try to trim it so the relay just pokes through the top. Also wish I had something that was a better match to the stock wiring harness sleeving, but the electrical tape isn't terrible looking and it's easy to re-do should I need to add more stuff in the future. I got lucky that the hood hinge juuuust clears when closed; forgot to check when I was mounting it.