I bought a parts kit cut like this one
Photos

I am concerned that welds shrink a bit when they cool
So the top strap needs to be perfect so it will have the correct cylinder gap
Is there a way to compensate or if I put a spacer inside the frame where the cylinder goes, will it hold it correct as it cools?

I am a ok welder on fixing equipment where it has not been an concern about small shifts
I know building a jig to keep it aligned is expected

Seems to be missing most of the grip.

Who has been cutting up Model 10s? That’s downright depressing.

Pro level welder needed, and a machine shop.

That is how they make gun buybacks economically viable.  Also, some departments do this with guns ordered destroyed.  I understand there is now a bill being considered which would ban this practice.  This is what they call "zombie guns".  I bought several a couple of decades ago, as when they were cheap it was an economical source of parts.  I haven't seen very many the last few years that even came close to being a reasonable deal.  Maybe a few Glocks and 1911s have been brought back to life by this path, but I would think not very many.
OP, good luck.  Getting that kit back to being a functioning revolver would be a labor of love.  If you can pull that off, I will nominate you for Emperor of WECSOG.

Well...Jim Clark made a name for himself building "long slides" by welding two slides that had been de-milled(cut) together. Almost to the point that you couldn't tell they it had been done. Also had a reputation for accuracy. That was years ago. Technology has improved quite a bit since then.

Loading a welded high-hardenability alloy steel member in tension is foolhardy IMO.  You're asking for a trip to the hospital.

Not a welder but imho a ‘fair’ welder 🧑‍🏭 isn’t gonna succeed. A ‘Master’ welder with careful and complete jigging combined with a good machine shop, ‘might’ make it happen.  Not just fabbing and welding the grip portion but reweldijg the top assembly to the frame? For the time and effort you’ll spend, you could put those master-class skills to work and make enough to buy outright a couple of Korths.

If alignment isn’t PERFECT then the gun is gonna try to come apart every shot, accuracy will be nonexistent. You’ll warp the crap outta the lower portion that has all those delicate cuts. Once warped l, the side plate isn’t gonna fit right. Etc.

Sorry but if you thought you’d bought a fixer-upper that a few tacks would get you a cheap, functional gun…I don’t think so.  

Truely not trying to be a downer here but other than just playing with it for giggles, I wouldn’t trust it.  Use it for parts as intended.

Missing actual parts of the frame like most of the top strap and the grip. By the time you buy a couple to piece together a sketchy one, you could buy one in VG shape and not worry about it coming apart and being worth nothing on the resale market if you ever decided to sell it.