Has anyone ever done this? What was used for the heater core? How were the coolant lines run to the heater? I'm in the Northeast, and heat is necessary if I want a driving season that's more than 4 months long.

I haven’t done this but have looked into it. JEGS and others sell a small box with a heater core and a fan. I would hook it up to the existing wiring. Mount the box in the trunk and drill holes for water hoses and one for heat. Split the heat tube inside the engine bay and route down to the heater tubes. From there you just use the factory controls to route heat down or up for defrost. I think this would be an easy solution.

With a Subaru engine you might be able to mount the whole thing in the engine bay.

Countless builds on this site with under dash AC/Heat Units.
Renegade sells everything. https://www.renegadehybrids.com/914sbc.html
Otherwise any hot rod shop can fix you up.
https://www.oldairproducts.com/
Something similar to this under the dash. https://www.oldairproducts.com/product/unde...-inside-package
https://www.southernrods.com/a-c-and-heat-components/

http://www.914world.com/bbs2/index.php?sho...105071&st=0

Uses a '94 Mustang heater core and modifies the stock fresh air box.
I went a bit overboard and used a heat gun and block of wood to reshape the box so the core fit better. I haven't yet finished but I think it's a tidy solution.

Post 40 in here shows how I built an abs box for a spal fan and Mazda 626 core. This was practice for future state when I need the AC core in there too!

http://www.914world.com/bbs2/index.php?sho...6435&st=20#

I like Chris’s solution too.

Lots of options and I went with an under dash unit. First few posts here show my approach.

http://www.914world.com/bbs2/index.php?sho...=341311&hl=

I am happy with what I have, but if I were able to do it over I’d find a way to use the factory side vents also. Being used to driving modern cars I notice the lack of heat coming out of them when really cold.

This site and it’s members continue to amaze me. Thanks everyone for the suggestions and helpful information.

I’m also interested in doing this… anyone have trouble with the heater core being exposed to rain fogging up the windshield on a cold rainy day?

There is always the alternative of keeping the existing OEM heat system IF the plumbing of your H20 exhaust system has space to install the Turbo or Cessna style heat muff. https://www.aircraftspruce.com/search/searc...p?s=heat%20muff

I added some baffles and drains that have worked well. I have driven in rain, snow, and sleet. Wouldn’t choose to do it, but once the car is warm there is no fogging, but I often crack the window to keep air flowing through. The cabin is pretty well sealed otherwise.

I guess it depends on how cold your climate is. In so cal or nor cal, I find it works better to put outside air as defrosters and hot air out the bottom. Otherwise the heat to the windshield to defrost it would roast me.