The cracks between the sleeves is common on most of the Oliver engines of that era, and should not be a problem.

I believe you can still get the 3 1/2 piston and rings, although the 3 5/8 will drop right in. You can check with Korves Oliver for those at <!-- w --><a class="postlink" href="http://www.korvesoliver.com">www.korvesoliver.com</a><!-- w --> 

The correct color is Meadow Green, Martin Senour code# 99L-3751. The white is called Clover White, PPG brand # DAR 46536.

Dumonts make the fiberglass grilles for the 550. You can get their contact info by visiting them at <!-- w --><a class="postlink" href="http://www.oliverdecals.com">www.oliverdecals.com</a><!-- w --> Click on reproduction parts to see the grille. Dumonts also have decals for the 550, in case you need them as well.

If you need anything else, just let us know.