Kirk frame works. Flex stem works. Biopace works. clips/straps for pedals. Super long seatpost for arse in air positioning. The brifter mtb stuff works. Disc rear wheel works (perhaps with a smiley acid face). Super short handlebars. Bar ends. Brake lever extenders so you could use them from the bar ends. Maybe an upside down suspension fork. Maybe one of the daft spoke patterns for a front wheel. Porcs or Farmer John's tyres. But also add crud claw and those rear mech protectors that used be on everything bitd.
You just described my dream 1990 bike.
I'm going to throw in 150mm stems and 500mm bars. My STS is still in its original cockpit set up. The brake barrel adjusters almost touch in the middle. Also "NORBA" geometry.
My first MTB was an 80's Raleigh Maverick. Short stem, riser bars, slack head angle and long wheelbase and chain stays. Then the racers got involved and we adopted road influenced geometry. Great for Americans racing on wide fire roads, crap for technical riding. 35 years later, we are finally back where we started,