Looking good and glad you haven't been put off by the other miserable B*****ds:heehee:

I'd go with the first option but if it was mine I would put the y-axis lead screw between the blocks, like you have done on the x-axis. The gantry could also do with a bit of stiffening to prevent racking, either another plate on the other side or a length of 8020 bolted to the ends and the y-axis plate would really improve it.

the lower gantry fixing may also be a weak spot and again I would use some 8020 (or angle plate) to strengthen the base plate and prove a larger fixing surface to the gantry.

How did you get on with thk rails?