Freewheels generally have a stepped diameter.
I think building one up with a different spacing would be quite time consuming to get the stack to tighten up properly.
A comparably easy - but pricey - way forward would be to buy one of these:
https://www.sjscycles.co.uk/freewhee...eewheel-1136t/
and use as a parts donor.
Merely replacing spacers might not do the trick. You might need to take sprocket thickness into consideration as well.