If you run an idler then you really need to use a "toothed" V belt.
You can't go wrong with a March kit. For $840 you'll have a beautiful set up with all new pulleys, everything matching perfectly and a single serpentine belt. It puts a large "wrap" on the alternator, so even if you upgrade to a 140 amp it will never squeal. It mounts the AC compressor low, on the passenger side, and out of the way so you don't have big ugly hoses running over your pretty engine.
It's one of my favorite parts of my build.
I'm generally pretty short on cash, so spending $840 on a serpentine kit is kind of out of the question. Besides, I've already dumped a bunch into the March V-belt pulleys I currently have, and I'd like to keep the KRC pump if at all possible. I am intrigued by the idea of using a multi-groove pulley to act as a sort of PTO for the AC compressor. Perhaps I could reconfigure the power steering belt to skip the water pump, and then run the AC off of the extra water pump pulley?
Edit: looks like the PS belt would just hit the WP pulley. However, there is a 3-belt water pump pulley for use with smog pump equipped cars. https://www.summitracing.com/parts/t...view/make/ford
Proud owner of a '65 289 coupe. Equipped with Edelbrock Performer intake, Quick Fuel 680HR carb, ported stock heads, 282 Magnum solid cam, Hedman longtube headers, MSD ignition, and decked and ported heads. T5 transmission with hydraulic clutch. Griggs Racing GR350 suspension. 8.8 rear end. Griggs front & Wilwood rear brakes. Many more mods to come!