I'm with joedoh, set the engine in and get it where it needs to be, mindful of the fact that you will need to run a column and steering shaft as well, and then work on the column. remember that the suspension will move so leave room for that. remember that the exhaust is going to get really hot and u joints generally don't like to be cooked so keep some distance there. the u joints will need to be phased (google that but it basically means they need to lined up a certain way) and also are made to be used within certain angle parameters, too much angle will cause the shaft to speed up and slow down as it turns a single rotation. that is one reason why we try to match angles on the ends of the shaft, one end compensates for the other end and the output ends up turning the same speed throughout the whole single revolution as the input. you may need a center support bearing, if you need more than a single connecting shaft or have a steep angle, long lengths etc. it is kind of important to do your best to match the angles at each end of the shaft.
these should get you started in the right direction so you understand how a u joint works and the do and don't of assembly when the time comes..
explanation of angles and how they affect shaft speed.
https://www.youtube.com/watch?v=gmV4qwLfOMY
https://www.youtube.com/watch?v=8M1aR41SVf4
https://www.youtube.com/watch?v=oMSM3QDXf64
https://www.youtube.com/watch?v=vKoSEQVEarc