I do 90% of the work on my car but I am having my engine built. If mine had gone back together as it was I'd have built that myself as I've no issues building engines and have built more than I can count at work. But I'm putting 3 - 4 times the power that engine is meant to have put into it now so that's a very different story and the point wear you with out doubt need the time served experience to get a engine that will do the numbers you want and reliably