Is a low port intake manifold from a sr20det fit
on a sr20de from a 200sx se-r(high port)?

well first a 200sx has a low port *** the injector ports are lower in the head and 1991-1993 is high port.I know a highport bb det intake will fit a high port de

okok!
so is my high port(TMIC) sr20det manifold will fit my low port sr20de(1995 se-r)?

no it wont fit. unless you mod it too ;)

will a high port classic head bolt on a BB without mod? if so, could i use the 7mm valves and all the components from the BB on the classic head? i want to get a classic head ported and polished and use it on my DET (with minimal downtime)

Yes this will work but if you use a de head and 7mm valve you will need bb valve guides also.I am going tpo do the same thing

i'll use the valve guides from my BB head when i reassemble the DET w/ the classic head.