I,ve no idea about mix and matching IP parts,.
My experiences,.
i got better fuel mileage from low pressure poppet motors,.
don't put a pencil injector pump on a poppet motor,. it takes out the head gaskets quick sounds bad,. ,.
Put head studs in and the little motors are good to go for a long time,.
last one i did i added roller rockers,. 2 large remote oil filters,.and a toilet roll type bypass filter,.and a set of headers,.
they'll take more timing than the factory says and are noisier but happier with it,.,
check youtube for guys with turbo's on them,.
My 81 chev caprice got a best of 41mpg running interstate from east coast to west coast,.and with the advanced timing and a manual glow plug controller,. would start at minus who knows what temp,.use bosch duraterms, they won't swell up and pop,.
after you're done playing with the diesel,. you can use it for an anchor and add a 455 olds for a fun only ride,.

Clean oil is the key,. olds motors use an aluminum non adjustable rocker arm pedestal, dirty oil wears them fast, .keep a decent timing chain in it, as they stretch fast and the pump timing gets behind,. they slobber and then crap up the oil twice as fast, not to mention poor starts and less than optimimum mileage,.
200R4/700R4 work well BUT, you should have 3:23's or 3:42's, then the 350 seems quite peppy compared to trying to pull 2:21's,.

I,m keeping an eye out for an el camino diesel for another daily driver,.
My all time favourite was an 81 burgundy with burgundy interior fleetwood brougham with an indash 8track CB combination,had the radio peeaked and tweaked etc,. i was the 'cadillac kid' of course,..i put slotted polished aluminum mags with G60-15 tires on it,. looked cool,. back in the day,.

Nick
Old 5.7 diesel junkie,.