RBs and LS engines are the most common swaps, but some people use Nissan VQs as well. Apex Engineered offers a front subframe with mounts for your choice of L, JZ, LS, RB, and VQ engines. The VQ would let you put a CD00A behind it if you wanted a brand new trans.
https://www.apexengineered.com/store/p7/Front_Crossmember.html
If you want to stay with an L-series, Datsun works (sold through Godzilla Raceworks) offers kits to put either a CD00A or TL70 (BR-Z trans) behind them. Both brand new, more modern options.
https://www.godzillaraceworks.com/drivetrain