Why not just take the LS you have and make an LS/Vtec. Your gonna have to use a tranny other than the CRV's, like your ls tranny. You can have you block resleaved to handle 40-60psi of boost. and you can put Forged pistons, rods etc into your LS block. Get a B16a or b18c and put it on. With a B20 block with a b16 or b18c head you have to have the head redone so that the dish in the head is the same size as the CRV pistons. b20's have an 86mm bore, b16 and b18's have the same bore of 81mm. Also you will run into issues with piston/valve clearences at high rpm if you dont have the pistons cut so that the valves dont hit the piston. To make a long story short, its gonna take more $$ to get a CRVTEC to work than a Ls/vtec would. you already have the block, a b series head is easy to come by and you have to use a Bseries head anyways on a B20 build up to make the most HP seeing how they arent a Vtec motor to start with. Thats the short version of it but do a serach for more info about ls/vtecs and b20 buildups (aka. CR-Vtec's)