I watched both vids on youtube - you are probably insane - but in a good way!
Try not to hurt yourself, and good luck with the crossbow! Word of warning - if your prod lets go in a certain way at full draw, that thing is going to take the top of your head off so over build it and be careful.
If it works - should be impressive. I like the idea of a long power stroke crossbow.
If you want, I can send pics of a testing prod that was made for the MR replica bows before Simon Stanley came along.
All wood - so doable without metal parts!