Without much hassel, you don't have alot of choices, because regardless of what engine you choose, you'd want to change your wiring to the 4 injector setup. The Dual Point Fuel Injection you have now only uses 2 injectors.
If you are willing to change the wiring to make it work, I'd go with a d16z6 out of a 92-95 Civic EX or Si. 125 HP, bolts to your transmission, and all you have to do is wire up VTEC and the extra injectors.