I am currently in the process of swapping a Datsun A15 motor
with 5 speed into my 65 Sprite. The trans is the one that Mini
Motors and Mini-Mania offer conversion kits for.
The engine is a pushrod, non-crossflow 4 cylinder. It is layed
out very much like the BMC A series motor. The overall size is
very close to the original motor also. In stock form a A14 is
rated at about 70 h.p. The nice thing is that this is a 5 main
bearing motor with forged crank and rods and an aluminium head.
It is also an unleaded fuel motor.
At one time there was an SU carb setup ( Hitachi ) avaliable
from Datsun that was used on cars in Japan and maybe Austraila.
The large port cylinder head is still available from this motor.
There are also Weber sidedraft setups available. The motor was
available in 1200, 1300, 1400 and 1500 cc versions in the Datsun
1200, B210, 210, F10 and 310.
When the B210 was raced in IMSA these motors put out about 150hp
at 9500 RPM with the stock crank and rods.
The transmission is almost exactly the size of the Sprite tranny
and the shifter even comes up the same hole.
My plan include a negative ground conversion using the Datsun
altenator and the Datsun starter. The motor also has an
electronic ignition which I will use.
I have corresponded with a fellow on Compuserve who has done the
conversion and is very happy with it.
If you need any more info, just let me know.