I reckon due to the overall state of the car you're drifting more towards restoration levels of work simply because of how bad it is and how hard it is to source parts, even if the finished car won't be to "restored" condition.
Personally I'd sack off the interior entirely and concentrate on getting it reliable and good to drive first and foremost.
With the mechanicals sorted move on to the bodywork, once it is all straightened out strip the interior out and get it painted.
While the interior is out you can try and get it sorted.
That way you break your budget and time up into manageable chunks. It's easy to get carried away and jump into one job once another stalls but you just end up digging yourself a bigger hole to climb out of. Hence why I have a Dolomite with no engine AND no wheel arch...
You've already shown you're adept at getting job done, you know what is needed and where to get the stuff, you're just rushing ahead of yourself and leaving yourself with a mountain of started jobs which need finishing.