You don't need a 87 Cylinder as long as you get reed cage and manifold for a later cylinder. There's a lot of junk out there as far as used engines. 25% of the ones I see are not worth saving the case damage is too extensive and parts were just running too long too loose. 25-30% with a crank some bearings seals and cylinder are ok. The other 50% just need bearkngs seals a crank rebuild or new crank and a piston n bore.
I've been seeing a lot more bad cases lately,
**** welded. Bearings fall out etc. As time goes on it will get worse and harder to find clean cores to start from. Especially as new parts become unavaliable. If you have good tight case's I say rebuild what you have . A new hot rod crank or rebuild you old one and a different cylinder or resleeve and you'll know what you have.