Talk to Kelly Peterson (he goes by Kelly on here) - he is the Gamemaster Jet guru. You can use the search function at the top and send him a Private Message.
Here are my thoughts (I'm no guru, but I have 5 Jets, and have been hunting with them the past several years)...
Jack used a braided string material, white with red servings. If you need more Charlie Lamb on here makes them with original material. Of course don't shoot fast-flite or non-stretchy strings on your Jet.
They are cut about right at center, not past for sure.
I use about 1/2 to 5/8 inch above center for nocking point, and for the brace I use about 8 1/4 to 8 1/2 from the throat of the grip (not how Jack measured it) this is at or a bit higher than the high end of Jack's recommended range measuring from the heel of the grip like he did.
I have gotten to using a cut down Bear weather-rest on my Jets - of course he made them originally with feather rests - that works fine too. Trap on here makes good ones if you need a replacement. I had trouble shooting Jets off the shelf since it is so wide and flat - I did have good results building up a narrow shelf with foam, but these bows are made to use an elevated type rest from the start.
From my 50 lb Jet (pulling 29 inches, so get a couple more pounds out of it) I use a 2215 with 200 grain point or Axis .400 deflection arrows with 200 grain points.
Oh, and if you ever think of selling yours, drop me an email, please
Ryan