I am currently in the process of a similar build but with a Kubota D1105 diesel, I am in the final run of getting it driving under it's own power and plan to make more updates on it here soon. You can check my profile for previous threads to see what I had to do it it. I had a little more hack and slash to do to mine but it's what I had, all said and done I think I spent maybe $1000 on the engine including rebuild as I was looking at a similar route as this but the prices of even used diesel motors pushed me away. Glad to see I'm not alone in the pursuit of "big" diesel swaps, looks like you've done a much cleaner job than I have though and started with parts that are in much better condition.
Some things to note from my perspective on my build, may or may not be helpful for you:
1) Having a mechanical PTO for either the rear hitch or the middle is next to impossible. I have worked out a mid PTO idea but have yet to try it and for the rear there's just simply no room unfortunately without large amounts of fab and modification.
2) With these diesels they're far heavier typically than the stock Onans (not to mention significantly more torque-y) so I'd recommend some frame reinforcement at some point, especially if you are planning on adding a loader or sizing up the 3pt category. Also, the weakest link typically is the frame cross-section change by the brake drum (extensively covered on this site) and the front axle and mounting area (@bobneumann has a fantastic video on a new front axle build on his YouTube channel). The frame is roughly 10ga C-Channel which is strong but given enough twisting loads will yield pretty quickly.
3) With great power comes great responsibility... Curious to see what pump sizing you're planning on doing and what kind of attachments/valves you're going to throw on there. I have found the hardest design problem on mine has been the hydraulic routing and valve placement. Either way 20hp is a lot to play with in something that size and all hydraulic.
Some things to note from my perspective on my build, may or may not be helpful for you:
1) Having a mechanical PTO for either the rear hitch or the middle is next to impossible. I have worked out a mid PTO idea but have yet to try it and for the rear there's just simply no room unfortunately without large amounts of fab and modification.
2) With these diesels they're far heavier typically than the stock Onans (not to mention significantly more torque-y) so I'd recommend some frame reinforcement at some point, especially if you are planning on adding a loader or sizing up the 3pt category. Also, the weakest link typically is the frame cross-section change by the brake drum (extensively covered on this site) and the front axle and mounting area (@bobneumann has a fantastic video on a new front axle build on his YouTube channel). The frame is roughly 10ga C-Channel which is strong but given enough twisting loads will yield pretty quickly.
3) With great power comes great responsibility... Curious to see what pump sizing you're planning on doing and what kind of attachments/valves you're going to throw on there. I have found the hardest design problem on mine has been the hydraulic routing and valve placement. Either way 20hp is a lot to play with in something that size and all hydraulic.