FWIW, my thoughts:
- V8 so a LS/JZ/RB, Anythings possible at the Zed shed, however this could potentially be the most expensive option. I need to do a lot of research into it, but i'm probably looking at £10k+ for this work - I need to have a chat with Wasso and Bizz. Unless you think you'll have £15K spare, I wouldn't go down this route. Given your situation now, and the fluidity of it, I'd discount this straight away.
- Forged Engine Build - Straight up around £7.5K. See above.
- Buy another DE Engine - £1000-£2000, the only issue with this is, it's like a lottery. I could buy a mint engine, or I could buy a dog of an engine. You can get the engine tested and everything before it goes in. You worry about this applies equally to the V8 swap or the forged engine build: Really, you never know it'll all be fine until you get it running. Even if you bought brand-new, it could still be a duffer!
- Buy another Zed (Cat C/D) Or something with Rear end damage ( Or any damage) - This way I can drive the car and get a feel for the engine etc. Plus I can then split the car and sell spares etc. - Not a bad option at all, if you have the time and space.
- Keyser has 3 engines at the Zed shed which we could possibly make one engine work out of all them. Again, worth considering if the above two options don't work for you.
Whatever you decide, you have our support. This might be a good time though to start looking at getting your own place sorted, and get some stability though