The E and the CA came out the same year 1981 for FWD use. A main goal was overall shortness. E replaced the A-series and CA replaced the L-series (as per the Nissan Service Bulletin). That's why they share some of the same timing belt/valve train parts. See Nissan E Engine for more details.

SR is a heavy one, not sure why they ever came out with that one, I guess to replace the 2-liter class (L20B/Z20/CA20) with a 16-valve design. The KA head is superior and bigger displacment to boot. I would go with a KA24DE DOHC 16-valve engine in a 1200. 14 second quarters with a stock KA!

Or a CA18DET is even better, lighter and more HP but more complicate what with the forced induction.

CA or KA, you can use the 71B 'stumpy' 26.3" overall length tranmission, fits the stock shifter hole and uses the stock 1200 (auto) driveshaft. That is a really rare transmission in the USA, only a few 720 pickups had them. If you use a "short" 71B you can shorten the driveshaft, and cut the shifter hole about 4".