TBH despite the work, which hasn't taken long anyway, I had two choices.
Buy this car back for the engine as I'd already spent loads on it and done little mileage since.
Or buy another Astra with a view to doing the engine again and still find rot when the carpets etc were lifted. Also I know my old car inside out and it helps that the last owner did zero mileage in it since he bought it from me eight years ago.
The engine has done 12k since the re-bore and crank work, so still hardly run in yet.
The engine work wasn't cheap, the pistons cost me £400 back then and are about £550 now, add the boring work, crank regrind, con rod work and uprated bolts, lightened flywheel, head polish and flow along with valve stuff, gasket set and all the time and effort and the I can safely say that I bought it back for a lot less than those costs alone.
There is other stuff to consider too, like suspension mods and the head on this one is rare. It's made by Cosworth and not GM. Not many about now and worth more than I paid for the car on its own.
I did think at the purchase time that if the chassis turned out to be scrap I would still be quids in on the engine alone. By the time I've finished it'll be solid at a good price all round .... well that's the plan anyways.
It's only a little welding after all

Oh, and I'm enjoying the re-build, great to get back into a bit of car stuff .... bike next... maybe...