A merlin jet engine will fit Christ anything will fit but will it be practical and achievable and drivable and registrable??? These are all questions that need to be answered not simply yeah it will fit, custom cross member and new tunnel!!!

If you have sr20's you can simply look at the motor and know there is no way that will fit in a 1000 and the bonnet actually close.

Back to the original post, a hottie a15 or a, dare I sa it, 4age or gze would be the go and about the biggest motor you could get in these cars. Besides everything that has been said you will not get an sr20 engineered in a b10.

I have fitted many different motors to many different datsuns over the years, I am not offering my advice as a way of shutting down someone else's enthusiasm, its facts of the matter