Questions about modding a Sears-Silvertone Organ amp into a guitar amplifier

[DBP2529]

Hello! So, I Have a working Silvertone 4751 Amplifier out of an organ I got for $30 from a local man who was selling it on craigslist in my area. Now its been sitting on my shelf for a while and I finally came up with an idea of what to do with it. I was looking at some Marshall amp schematics and saw the preamp schematic for the JCM800 and I noticed that it uses 2 12AX7 tubes for the preamp (excluding the phase inverter) and I also noticed that the plate voltages are similar to what the organ amp puts out. So I figured, Hey why not redesign the organ preamp to use the high gain circuit out of a Marshall amp and get a more distorted tone out of it.
Now, I combined the 2 schematics (which I stole from the internet) using MS paint (image linked below) on how I believe it should work and from my understanding it should work alright but my concern is would the high gain from the 12AX7's be too much for the 6AQ5 tube to handle causing it to squawk? Or would the voltage coming out of the PT be too low to work with the Marshall preamp circuit? Also, the Marshall circuit has 2 filter capacitors (50uF) that I believe are unnecessary due to the existing 40uF caps on the organ amp's power supply. Anyways, I'm not a electronics professional and I just wanted some input from some people who have more experience than me to know if this is even a feasible mod. 

[shooter]

the filter you marked "necessary??", keep it.  SE amps want good filtering
that pre-amp has enough to drive a KT88, so an AQ5 is gonna beg for mercy!


it can be tamed so make it work and then tweak it as needed

[DBP2529]

Cool! Also I noticed I have 2 volume knobs going to the power tube in the schematic. Probably don't want that lol! It probably wouldn't hurt it but there is not a ton of chassis space for knobs.

[shooter]

i'd pencil in a 1.5k grid R for the Pa tube,  fwiw I used a 500k-lin as a MV on my el84 build

[DBP2529]

Ok, So I revised the schematic with that 1.5K before the Power tube and I removed the unnecessary volume pot. Looking better?

[tubeswell]

Another idea for switchable single/parallel/cascaded V1

When plugged into V1a in parallel mode, V1b is bypassed*
When plugged into V1a in series mode, V1a is cascaded into V1b
When plugged into V1b in parallel mode, V1a and V1b are in parallel
When plugged into V1b in series mode, V1a is bypassed*


*the different Ck on each stage gives a different half boost point for either V1a or V1b (More noticeable if you could go down to 0.47uF on V1a)