Amy,
To answer Paul’s questions above, to my knowledge all of you 289 stuff will bolt onto a newer 302 “short or long” block. You can even use your 289 heads on a short block, but that kinda defeats the purpose. Although stock 302 heads are not much different than you 289 heads until you reach into the era where they offered the “P” style casting which are mid to late 90’s stuff.
If you buy a crate engine from Ford or anyone else, you will need to use your oil pan, pickup, and the front timing cover from your engine. This will allow you to keep the stock oil dipstick, and stock water pump to match your new radiator. Another major thing is the vibration damper and flex plate balance. Newer 302’s used a heavier balance on the engine. The newer vibration damper has a 4 bolt setup for your lower crankshaft pulley. New aftermarket pulleys are drilled both ways (hey others on the site, help). Anyway you may be able to use your stock damper and flex plate. Help again out there! And again if you want to realize full performance from this crate engine you will need better exhaust.
I still think your engine may be fine. Clean up a piston top with a wire brush and see if it is stamped for an overbore. Get that starter out and give me some numbers above it. It may be a date correct block and maybe the original engine even if it is not stamped.
It sounds like you are in need of a prudent fix that does not spend all your money at this time. I bet that engine will run just fine with the heads redone and assembled properly. And the heads will be ready later if you want to do a total stock rebuild. Get me some date codes young lady!!! Time to get smart on date codes! I can come over and help!
I live in Bremerton, have hand built at least 20 Ford engines in my career from mild to wild, started new motors way more numerous than that. I bleed Ford blue, and the movie Bullitt that I watched in the theater in 1968 started my love of Mustangs. Back when they were not cool. I drove about the only Ford in town those days…. We used to be a big cruise town in the early 70's.
Rob