Pulling the head may be difficult to do in a junk yard, and getting someone to sell me just the block would be tough as well. I will do my best to investigate any z22 block I come upon, thanks for the photos those are super informative. I'll be sure to read through your thread.
Honestly when I think about spending more than 2k on my 620 it makes me feel like...it's just a 620. It has a lot of value to me, but I respect all of your opinions and would like to own a Z or a 510 some day and if I have a lot into my pickup it will be tough to get into anything else. So I'll just rebuild what I have. I didn't realize my U67 head already had larger valves than other L series, that's really interesting and seems like a good thing for my application. If I go with a rebuild on my l20 (possibly a mild bore for larger pistons like flatcat suggested, I'm sure the 38/38 would work great but I want side drafts, just for fun), what kind of costs should I be expecting? I would also be finding some dcoe's, after reading through the R1 thread I think it's a bit out of my league. Would I want to port my head?
Yes the U67 head has large valves and intake ports, the only reason it is not the sought after SSS 219 head is because it is an open chamber head design.
If you rebuild your block and choose the right pistons, that would basically turn your U67 head into a SSS 219 head, meaning if I build a LZ22 with stock type Z24 dished pistons and use a closed chamber head with big valves and ports I will have an 8.9 to 1 compression ratio, if you built a LZ22, use less dished pistons, and use your U67 head, you also can end up with 8.9 to 1 compression ratio, I have no advantage over you, your head is fine, it's all about information and choices.
Flatcat mentioned using 280zx flat top pistons, if they with your head work out to somewhere around 8.9 to 1 compression ratio that would be one way to go.
I personally run dual SUs on my L series builds, I also run stock cams as even using an RV cam robs one of torque, I like my torque and I am not on a circle track going around in circles at a steady 7000rpms, so the stock cam is a good choice for me.
I like SUs because I understand them, I don't like down drafts because I don't understand them and it seems the only way I can get a good one is if I buy it new.