If you live in Cleveland (where is snowed on opening day) or Boston (where their games are probably going to be cancelled because of snow) you really believe in Global Warming and don't need a working heater. Otherwise, I would not use the 'hose jumper' method and opt for a new core, hoses and clamps. (I really hate doing things twice.)
Jim

 

seemed like an all day project to replace heater core,,,drop 8 track,,,drop ac, dark close quarters,,,made up my mind to do H- Valve/hose setup to divert radi fluid, if leak springs,,it buys me time to switch hoses around till I got time replace core

 

I have a '65 Stang w/o ACand I just put in a new heater core, gaskets, seals, plus a Flush and Fill on Saturday. The whole job, from start to finish, took me about 6 hours. Removal and diassembly of the box was easy. The hardest part was cleaning all the metalpieces anddoorsthat were in the box halves. They had alot of debris and rust on them. Wire brush, Sand paper, paint, trim adhesive, attach new gaskets and seals, then reassemble. I also put in new cables, a new fan switch, and defrost ducts. The heat works great and no leaks!!!!

 

Hey JChase. Welcome to the site. You sound like you know what you are doing.