Thunderbird Rig

[TBird#111]

I have recently acquired Thunderbird #11 which is being restored with a target launch of May 17th. She came with no mast or boom but I have a mast and very old standing rigging from another Tbird. I fully intend on replacing the standing rigging with new but am concerned about how to get an accurate measurement for the new shrouds and jumpers. I don't feel comfortable with using the lengths of old rig off another boat. Is there a known measurement out there which I can compare? Or I guess we lay the mast out on some template and take a wag at it. The jumpers are easy and the shrouds should be close, but I'm really wondering about forestay and backstay lengths. Would the original plans be within tolerance of any errors which could be adjusted out through the turnbuckles?

And another question involves how I run my halyards and running rigging. I don't have a deck plate to attach blocks since the mast is keel stepped, but was envisioning a stainless strap around the mast about 14" above deck which would have small loops welded to which I could attach turning blocks at a height which would run clear of the cabin top and straight aft thus eliminating climbing up the forward windows. Can someone guide me as to the working loads involved with such a design? For sake of illustration, I imagine something like a large radiator hose clamp with the welded loops on the side to accommodate the blocks. I suppose the clamp would be about an inch wide and would need to be screwed into the mast, but would the loads on the block be too much for such an arrangement?