Obviously ,whoever rebuilt it may have lubed everything on assembly.And it probably has original jets in it, and hopefully the person who rebuilt them knew what they were doing.So, providing you know how to install your new engine,bleed cooling system of air, and settup oil cable free play properly,fire that thing up.Get it unplugged of any assembly lube,dont idle it too long,and use on/off shots of throttle till it doesn't smoke.Use this period to bleed air out of cooling system at the bleed screws located under seat at rear heat exchangers, this is a must!Also use your old plugs if they are OK.Take it for a run.Of course you could also let an experienced technician do the work for you? I'm sure there will be more posts on here telling you how its done.SteveC