>    I have owned my '71 passenger bus for many years now and love it.  Two
>years ago I had my existing engine rebuilt by a local guy who talked me 
into
>alignboring my existing case and regrind (3 angle) a set of used heads.
>Never again!  After only 15,000 miles the engine has low oil preasure, over
>heats, blows white smoke when started (leaking valve guides, I think) and
>low compression (100psi).  I'm going to yank this engine and keep it for
>smog checks while I put in a GOOD engine...one with a NEW case (read Gene
>Bergs catalog) NEW heads, full flow oil filter and dual carbs.

You're not, by any chance, losing brake fluid from the little reservoir
behind the driver's seat, with no sign of it dripping out any of the
wheels, are you? And maybe your idle is surging/conking out sometimes?

Mine occasionally blew out HUGE clouds of white smoke, ran shitty,
overheated, etc. Leaking master cylinder, combined with a bad one-way
vacuum check valve in the vacuum line near the engine. See other posts,
both now and from last few weeks.