can i get some light shed on my puzzle.

i have a 1979 datsun 1200 ute which i am doing a complete rebuild on. it came with an A15 engine, that will deffinately need a clean and possibly a rebuild.
i want to get a lot more power but dont want to get too costly, as i have heard it is easier/cheaper to do an engine swap.
i was wondering whether i should keep the A15 and work it or get a ca18det or sr20det.
if it is easier to swap to one of the other two engines what kind of work will need to be done to the engine bay and car body to allow for the engine???

any help will be much apreciated.
thank you.

try the search button or the tech section. as this would be the one of the most asked questions on this site by new poeple

and welcome to the site