I have a 2.0 bus engine (76/77) and would like to rev happily past 5k without problems. Is this as simple as 914 94mm P&C or 96 and putting some 2.0 914 heads? I realize the check tube is wonky, but does anything need to change to get this to work? Lifters? Pushrods?

Going for the budget build so AA and probably 2.0 AA heads

Remember some but most likely not all ;
Flywheel ,wrong off set,need to use 914 one,
Crank pilot output bearing in crank not in the flywheel as 914,can be removed,
Engine tin requires use of 914 parts to fit,
Cooling fan timing points differant so use 914 fan and housing,
Oil filler pipe on bus but not on 914,you can use the bus one but need to cut /close weld it above the dipstick lateral pipe, 914 oil filler breather tower from 914 becomes your new filler,
Most likely forgot sometimg but you get the idea,you need to be really careful and check the bottom end is sound,bus cases take a lot of s#it if it looks ok change the bigend bearings and get the piston pin bushes done sized for your new pins.
You know your stuff so not hard,cheers.