microbe,

Jim Carter's sells rebuilt 235 short blocks and heads. Since I have never bought one of these, I have no recommendation.

http://oldchevytrucks.biz/p/1955_1966/fullpage.php?page=100&session=1072954

I dimly recall that there is a company in Mass. that also sells rebuilt blocks (and/or will rebuilt yours) - maybe someone else knows the name.

Here is another lead but no prices: http://www.engineexchange.com/chevroletshortblocks.htm

Tim