1991 rmx/rm 250 factory build

So I purchased a 1991 rmx250 off of my twin brother that he bought and put in a corner for $800. After we cleaned it up I realized the odometer is correct at 40 miles, the inside of the motor is pretty much new. So I planned on just getting it running crisp and flogging the hell out of it till it gave up, but then... I came 🤤across the old rm125/250 factory bikes from 89-90 and I fell in love 😍, around the same time. Say 2 weeks ago 2/15/2022 there was a 2001 cr500 with all the goodies out in phenix with a blown 5th gear for $6500. The 01 cr500 is my white bronco and I passed up on it like 'That Guy' ... "sorry to dude in phenix"... 2 days before I was supposed to drive 2300 miles each way to pick it up. I threw about $4000 ish at this bike, becuase I found a site where I could get old factory works parts. So i could straighten out this old girls crooked teeth and make her a pretty again. So with that said, parts ordered are as follows.

#1. Aluminum gas tank
#2. Bob Hanna works replica swing arm
#2. Factory team works 53mm pipe
#3. 89-90 nos pro circuit 304 'old style silencer
#4. Ceet standard seat foam
#5. Two different suzuki tecnosol seat covers
#6. Gpi aluminum radiators with hoses and titanium hose clamps 'will upgrade radiators when motor is fully built'
#7. Nos procicuit ti flow through pegs
#8. Ufo plastics (yellow)
#9. 1992 rm250 old school talon hubs, 50t talon sprocket with excel takasago rims. Condition 7 1/2 out of 10 $400 ebay score!!!
#10. Boyesen Rad Valve
#11. Hammer Head
Shifter
There is still plenty left to buy or have made but
I might have jumped the gun on the exhuast and head gasket. I want to run this motor semi rebuilt with this pipe etc. For about 2 years or until it goes mainly becuase the pipe is awesome and matches the 53mm ehxuast port. I want to run a full ohlins set up the front end i think it will be easy to swap out triples and get ohlins forks, front axle/hub will need attention to make that work. Where I need help is with the frame and engine, most the information for the older Rm/Rmx 250's is scattered and depending on who wrote it is also contradicting. I'm going to run the motor thats in it with a light rebuild and some mods for now, and start the new motor build from the ground up. The new motor will be a kind of rmx300l 300cc big bore that Jeff Slaven's built in 1991 (I need to email him to pick his brain).. the new engine most likely will be built by Millennium technologies in Wisconsin. Why not Eric Gorr you ask? Called him he didn't sound very interested even said "why would you want to that to that bike. Its a museum piece at this age, something about third gear and him being busy" Personally I hink he lacks vision. Yes there's much better bikes to build etc but thats not unique. I want a one off white bronco... so back to the engine then the frame, the motor i want built will use 'in theory' a rmx250 bottom with a 300 cylinder and billitron carb, my rule for the bike is it has to stay period looking ish 1989-1990. So my big questions are will all my stuff mainly works swingarm, gas tank, seat, plastics swap over onto say 95-98 frame? Becuase from my understanding those frames were very similar and can be easily repainted blue etc. The bottom end's where also alot better from a full build stand point as well. Which year bottom ends were wide ratio? The horsepower goal will be 52 usable horsepower on the new motor so I want to start the build with the best possible rmx bottom end that I can. Any and all accurate information/advice is appreciated. I could use some knowledge from experienced builders.