FE Difference DX vs HF Motor in CRX HF?

[FritzR]

I was at the mechanic's shop checking on the starus of my D15B6 motor and again things are at a standstill. They can not find the wrist pins for the pistons. They have a JDM engine sitting there for a DX. It would be less to get this swapped into my car than the rebuild would have cost. How much decrease in
FE could I expect using the 16 valve motor with my HF Tranny in my 88 CRX HF?

I currently am getting 32 average around town out of a 90 corolla 3spd auto old EPA 26 - 29