It's not hard to have an A series flywheel redrilled to take the L series 200mm pressure plate. (If you fullas were in NZ, I could have it done for you for under $100) (Freight would KILL it though)
And TBH, you're pissing into the wind spending good coin on an H/D 180mm clutch plate. The 200mm L series one has 36% more surface area. A few years back I got an off the shelf LD20 P/plate, (with 300lbs clamping force) a 200mm plate, (With the linings bonded as well as rivited) and a thrust bearing and flywheel resurface for $168. I may only be running 10psi, but it has oodles of grab, whilest still being a pleasure to drive on the street. Compare that to what you might spend getting a poos and weese 180mm clutch custom made.
I can't vouch for the clearance inside a 4 speed housing, but the larger clutch fits inside a 60 series 5 speed housing no problems.

Now, with all this talk about the spigot.
The end of the input shaft need to be shortened, and turned down. They are both too long, and the OD of the Lseries input is bigger than the OD of the A series spigot bush.
The kick in the nuts is that there is very little to hold it by to turn it. When I had mine done, it had to have the tapered synchro journal locked into a tapered pocket so that it could be held to turn it.