This one tucked in pretty good. 
 

I re angled the belly of the pipe & tucked it in about 2" more
You can see the different rear cone angle here

  

Since we are talking about underslung exhausts, is this a correct pipe for this old Penton?
 

It’s been a while & lots of hours on this so an update...
 I took what Rt 360 said and went that way, altered foot peg crossmount and put a “special ding” in the pipe to get it as high as possible. 
  The engine fired up with no drama first time & over the last few weeks while finishing up details on it I’d practice starting it & taking some slow spins around the dooryard.
  Took some faster runs today, the clutch slips under full throttle but still it’s a great experience to ride it ... I’d switch between riding it and my other one (‘70 AT with 175 top end) .... nothing better than having the two side by side to compare. It’s been a while & lots of hours on this so an update...
 I took what Rt 360 said and went that way, altered foot peg crossmount and put a “special ding” in the pipe to get it as high as possible. 
  The engine fired up with no drama first time & over the last few weeks while finishing up details on it I’d practice starting it & taking some slow spins around the dooryard.
  Took some faster runs today, the clutch slips under full throttle but still it’s a great experience to ride it ... I’d switch between riding it and my other one (‘70 AT with 175 top end) .... nothing better than having the two side by side to compare. 
   
  The rear brake linkage was lacking the cotter pin allowing it to go under the rear tire locking it up- I thought the motor had seized. Stupid assembly mistake on my part. Lesson is don’t partially assemble something and think you’ll remember to get pins at the hardware later on...

So can I ask... You eliminated the battery by installing a voltage regulator? Well, I see alot of daylight under the seat... so I'm curious..
Sneezles61

 Lots of daylight. It needs a better air filter and later will get a small fuel filter once any dirt left in tank works itself out.
 Very simple wiring. Just a kill switch to ground the coil. The charging coil is still in there and probably produces electricity but the wires don’t connect to anything. I suppose it could have been removed without affecting ignition.
 Lots of parts had been taken off before I got the bike. Any surplus parts along with paperwork & Manuel are stored in a bin labeled 175 CT so in future somebody could convert it back to street use.