there is no such thing as a B20 vtec from Honda. Honda produced a number of B series that were non vtec including a B18 engine for the USDM.
There a numerous debates raging in regards to which head to use- B16 or B18. However, with Cams and valve train being interchangable, a large amount of people simply fit a cheap B16 head to the B20 and then install Type R cams. This was done to my CRX and it made for a fantastic, high revving car.
The one thing you will need to look for is a Golden eagle conversion kit-
http://www.robearracing.com/pd-golden-eagle-vtec-conversion-kit-hondaacura-b18b16b20.cfm
You may also want to consider a crank girdle if you were gonig to build it yourself.
The standard B20 does not provide oil to a vtec head. This kit allows for a suitable supply of oil. If it is of any help to you, i can put you in touch with a chap who has built a minimum of 50% of current B20 CRX's. He is the chap who managed a 12.7 second 1/4 and is incredibly profficient in producing reliable B20 vtecs. I went out in his original car and the engine is still going strong, 4 years on.
I'm assuming you are content with sticking with NASP? B20's as standard are a fairly weak engine compared to standard B16/18's so any form of FI requires a lot of work including sleaving. If turbo charging was an option, you'd be better off with a B16/18 and going from there.