might as well do the obd 1 conversion, you will have distributor issues if you don't. if you don't want to do it, you can get a one wire conversion done http://zdyne.com/convhome.html . it ends up being about the same price. no real need for a vtec controller just yet, but fields are basic and go for around $100 used on TR. 89-91 si would be primo for you. the 88 is a little different (spline count? can't remember) you need to change the mount under the timing belt to your old one off your stock 4dr motor. get the flywheel resurfaced and a clutch for a 92-95 si. if you plan on nitrous/turbo/sc anytime soon, you may want to get a good clutch (act, clutchmasters, etc.). don't want to tell you what to do, but general overhaul is easier while the motor is out. it is up to you..

more info here http://hybrid2.honda-perf.org/tech/sohcvtec.html