Before throwing away those priceless old Fet's, I'm not completely convinced the 134 is bad.  Fet's can be difficult to measure, and will sometimes show shorts depending on how they are tested.

And further to the good points RG and Roly have presented, you can't make extra power out of thin air.
Those regulators need an input voltage maintained at 3V more than than their output, so circuit adjustments may be required. 
This is assuming the power transformer has the capability to provide the extra voltage/current.

  A simple thing to try is using a spare cord to connect the FX loop send to the return.  Does that make any difference?

Here's some more reverb tank info you may find interesting, includes some sample circuits:
https://www.amplifiedparts.com/sites/all/modules/custom/tech_corner/files/spring_reverb_tanks_explained_and_compared.pdf

Is it a Medalist 4/10 like this?
http://www.ebay.com/itm/VINTAGE-AD-SHEET-2159-1968-GIBSON-MEDALIST-4-10-AMPLIFIER-/400606908345?rmvSB=true
If not, list the tubes that are in it.

  I think he left out the "62" in that link.
Here's a direct link to the pdf:
http://www.bonisaudio.com/code/Bonis_Audio_Doc.zip

  If Dr.Gonz' schematic is the right version, then E13 comes off one side of R21.

  So I guess that 550W from the amp must be peak or something?

 So what do you think the power handling of that 8" speaker would be? 

The typo is probably in the decimal place.  So more like $27.00
Amazon Canada has the same book for $34.99CDN, which would be about right with the  $exchange.  http://www.amazon.ca/Vacuum-Tube-Guitar-Amplifier-Servicing/dp/0933224974/ref=sr_1_1?ie=UTF8&qid=1443660566&sr=8-1&keywords=tino+zottola
Same price at barnes & noble.
Which AC15 top boost do you mean, the re-issue?

Quote from: dropanchor812 on September 21, 2015, 01:10:48 AM
-I don't notice a difference in sound coming from the speaker when I adjust the output waveform when following the directions in the manual.  Is this something I'm just going to need an scope to measure?

You can't follow the directions for this part without a scope, so you were not following the directions. 

Quote from: dropanchor812 on September 21, 2015, 01:10:48 AM-I can't get the center voltage down to ~45v as directed in the manual.  When the trimmer is fully counter-clockwise it only gets down to ~53v.  I'm afraid to turn it fully clockwise because I'm afraid I might blow something, but as it is fully counter-clockwise the amp still sounds great!

This reading is affected by the previous waveform adjustment.  Try moving the B4.7K pot either way and see if it helps you get the center voltage adjustment closer.

  It may pass voltage when you are pushing on it with your meter probe, but it may not pass proper current when you aren't touching it.
Try wrapping a small wire around it to hold it tight to the tab, or even solder it if you are careful and quick.  If you take too long with the solder iron you'll melt the solder in the fuse.

  Yes, it will be fine.  The amp will put out a little less power into the 16 ohm load, but probably not very noticeable.

  In case anyone is interested, attached is pg.2, with the more "complex" jack schematics.

  Those will be fine.  They are equivalent to MJ15015 but with a higher voltage spec.
For Peavey, it means one less part to stock, as they can use them for both MJ15015 and MJ15024 applications.
  You can consider it an upgrade, or "beefier" part.