Honda-SOHC

Hi. I'm fairly new to bikes, passed test nearly 2 years ago. owned an er5 and now ride a 98 zx6r but have recently taken ownership of some bits that resemble what's left of a cb750. I have owned this bike for 2 weeks now and so far found out the frame is a '76 UK model and engine is a '73 from America! No documents or reg plate to go from so any help with which steps to take to get the bike registered would be greatly appreciated? from here i will hopefully be able to get it running...