Hi Thomas, I reckon those lowering blocks look like a lot of fun. I reckon go for it. But it may be worth your while doing two things first. One is to pop along to your local suspension specialist. The speedway guys will point you in the right direction. And ask their advice on what mods you plan to do. You may find that these guys can lower the car and stiffen the suspension for around the same money it costs to buy your blocks!!(okay it may cost about twice as much). The front end is an easy stanza upgrade, but i would look into the 200b option. I actually think that alot of 200b stuff is sold as stanza anyway. You will need to spend a few dollars on new bushes and a bit of machining to get some bits to fit.Try to get aussie built datsuns , i think they had better calipers.Number two thing to do before you start is to have a look on this site in the tech. section on suspension upgrades there is an excellent part on upgrading a 1200 suspension to race spec. This is much less complicated to acheive on a 120y than a 1200. Also do a google search on "stanza into 120y" there is a complete and easy to follow diary of how to get the stanza bits to fit into your 120y. Personally i would look for an a14 motor(easy transplant, same bottom end) and they are far lighter than an L20b keep the standard carbie and pipes until you feel like throwing more money at it.
Good luck have fun and don't spend more than you have to!!