D-19 Diesel engine swap?

Even with a "free" engine, you're going to still spend some $$$$$ making it all work. If you are a narrow front end, forget it. There's no good way that I know of to connect the steering shaft and retain the power steering assist cylinder on the right side.  A wide front axle should be converted to hydrostatic power steering like the 180 is with an external cylinder.

Currently doing an F-2 combine 4-cyl turbo diesel in a D-17 S3 with narrow front. I'm using a specific size Char-Lynn orbit motor connected to the manual steering worm gear and hydrostatic orbitrol under the fuel tank. There is room to do all this and you have three more inches of frame length than I do. I won't know the results for a few weeks. I have a lot to do yet.

Don't get too excited about that combine engine just yet. Most Gleaner combine engines don't have a provision for mounting a hydraulic pump on them. I've had to pull off the front cover, camshaft and front engine plate and swap those parts for tractor parts and then spend $$$$$ for a 190XT hydraulic pump and drive. It will be all really neat when completed, but also a lot of work.

you surely don't use it as a main tractor doing lots of hrs? I'd go with the gas 262....you're biggest challenge will be finding a tractor governor

In situations like yours I've found it to be more cost effective to buy another tractor like the one I have and use my original one for parts or combine the two.