I had an email discussion with monster a few months ago and inquired if they could build a 700r4 with the np205 compatible output shaft and they said it's something they do all the time, so no problem there.
As far as the DIY4X crossmember I guess you could use the stock engine crossmember - I just wanted to go with a stronger piece with modern engine mounts.
Not sure I understand your question about cheating with the T-case...are you asking how far do you need to move the engine forward to not have to move the transfer case crossmember/Linkages/dshafts? I think it's 1.625" forward.
Proper technique for changing pinion angle - cut off existing leaf spring pads, (you'll need new pads to weld on), rotate the pinion up so the pinion/yoke is pointing directly at the transfer case output yoke. Then with an angle finder rotate it back down 2 degrees. Turn on the welder and burn in the new pads. (proper shop safety will keep you from getting hurt
)