There's not really any conversion it's more just swapping Si stuff into whatever non-Si you want to. As for the weights, I can't seem to find the file I had them saved in, and the CRX resource has had a redesign that leaves me perplexed, so the general rule to be aware of is that the newer the car, the heavier, and in each year, the range from lightest to heaviest will be HF, DX, Si.

If you haven't already, feel free to join the e-mail list I run for first gen CRX owners, there are several people that have switched over to EFI, at least one whose swapped in a B16, and others planning to go with a B series in the near future.