I think you have to decide what you are going to do with the car. Jule frames do well at auction but some people would say they are not original. The other replacements look like the original, and you would not have to tell people it has been replaced. I drive my car and planed to keep it for 20 years so the cost was resonable. I used to own a BN4 and the selling , prices for that model are lower. Perhaps I would not have bought a frame for that car, perhaps I would.
The question on the frame is the same as on any part that has been replaced. Is it still original and do you care? I wanted a nice driver. I have been to car shows where people have told me my car could be at one of the Pebble Beach auctions, but that is not why I built it.
I also recently finished a Triumph TR3A and an Austin Mini. I put too much money into both of those also, but I like them both. Hobbies cost money. Golf is probably cheaper, but not as much fun for me.
Jerry