RCA 9289 tube amplifiers

I brought the amp up slow on a Variac and it passed sine wave. 

That's good! Don't keep running it until the power supply has been refurbished. Otherwise running it is a classic way that a failing filter capacitor causes a power transformer to fail.

I thought it amusing Ralph weighed in here....

One of my employees refurbished a pair of the little brothers to this amp, that he got from an old theater. IIRC they made about 60 watts using a pair of 6550s. 

Dad always favored rebuilding them with Sprague Orange Drop coupling capacitors.

That is because back in those days they were the only game in town. A lot has changed since then! There is no way I'd use orange drops for any kind of rebuild or repair at this point- they are simply outdated.

If you are selling a set of these amps I would leave them bone stock, don't do anything to them and let the buyer worry about that. Anything you do to them can damage the collector value, even though they may barely work because the filter capactors are shot.

OTOH if you do replace filter caps, the only way to do it is to do it so well that no-one can argue with the parts choice and workmanship.