Frankenstein update-175 Frame/250 engine questions

[marsattacks]

First, thanks to all who have volunteered insight and time/effort/patience.  Hopefully the product will be a reborn Penton saved from the scrap heap.  Items 1, 2 and 6 are status updates. Items 3, 4 and 5 are questions.  The project so far (I have enlisted my brother in law as a conspirator):

1. The 72 Jackpiner frame is stripped to a rolling frame.
2.  The 77 250 engine is rebuilt (thanks Chicago Jerry!) and test fitted into the frame -- as predicted, it fits fine but we'll need to add some upper support tabs to the frame.
3.  The 77 250 pipe is in the process of fitment -- we are not sure what to do about the exhaust flange/manifold.  If anyone knows whether a MC5 style or JP style flange will work I'd be grateful for  your insight (we don't have a MC5 flange to test out, so I'd have to buy one and then see if it will work).  We have access to metal fab so if necessary we could possibly make a part.
4.  I have a spare Jackpiner pipe -- in a pinch will this be acceptable on the 250 engine?  I am guessing that it will be too restrictive and create too much back pressure but honestly I'm guessing since I don't know anything about fluid dynamics or wave theory so I'm not sure how badly performance will be affected.
5. If anyone has the Still Keeping Track articles on frame reinforcement/gussets available I would love to see them so we can reinforce the frame while it is stripped down.
6.  Up next -- the plan is to fit 35mm forks, a Lectron carb, a seat from a 1978 MC5 and possibly the rear fender from the MC5 as well.  Possibly also to fit Sun rims and a longer Harescrambler swingarm though this would entail further modification to allow for same-side braking.  The 78 MC5 seat and the 72 toaster tank make a pretty nice looking bike, though obviously it is an amalgamation of different eras.  Oddly enough the newer seat fits pretty well and will require minimal modification to the frame.

Thanks for any advice you care to offer.  Best, John

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[brian kirby]

Be careful, if you ever plan to race this bike in an AHRMA event the Lectron carb is not legal for Vintage. The carb would bump you up to Historic class with MC5s, Maico AWs and Suzuki RMs.

Brian

'73 Berkshire

[Mike Lenz]

the 77 pipe should go right on with the making of a rear mount tab. Not sure what you mean about the manifold.  77 pipe and 77 manifold, what is the problem? Jackpiner pipe will not work very well. The main support to do would be the lower of the steering stem. If you are attempting to use the old 72 rear hub, i'm afraid it will not take the abuse of the 250 engine. You can email me if you wish at [email protected]

[marsattacks]

Brian and Mike-- thanks.
@Brian--no worries no plans for Ahrma racing right now. Lectron was 30 bucks so hard to pass up.

@Mike--I was unclear--we don't have a 250 manifold and were wondering if it would work before buying one. Go figure-i received a 250 pipe and engine as a throw-in on another bike but no manifold. So your input is helpful.I have a Sun rear rim and hub from an MC5 so that looks like the plan.

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[marsattacks]

somehow when I post it shows up double.