I don't have all the answers, but I do know patience is involved. You need to focus and not be distracted into accepting less.
Shortly after I bought my Jaguar. ( Which I had been shopping for for years ) I started to look to upgrade the engine/ rear end.
What I wanted was the early 6.0 V12 Transmission and rear end. Only the first year and a half had the Forged steel EN 40 crankshaft. From late 1994 on Ford had invested in a sintered Iron crankshaft. Plenty adequate for the street considering how massive it is compared to the load it takes. The rear end because instead of a 2:88-1 ratio it's 3:54 and it has outboard disk brakes. ( much easier to work on and they don't put the heat generated into the differential).
Worse I wanted it cheap!!!!!
For years I've followed the insurance sites, Craigslist and Facebook. Recently one popped up and I knew it would be cheap. It was a sedan. ( same mechanicals ) but a tiny fraction of the price. Plus it burned the interior. So it couldn't be started. You'd need to buy it on faith it was good. One tiny prebid. Well below scrap metal price.
Just before I put my bid in my wife found out she has Cancer. Having gone through this with my late wife I know how expensive this is going to be.
So patience. •••••.