Since the stock ones are nothing more than tubes with partially pinched ends to fan out the spray, why not carefully bend the stock ones to where the pinched end still comes through the slots in the cowl or have it slightly retracted back to make it less visible and have the rest of the tube bent towards the driver's fender. You might then be able to use the stock plate that is welded to the tube and attach another bracket to it to attach to the metal underneath the cowl. If the tubing was to kink, use a tubing cutter and keep the last 2 inches or so with the pinched down end and after making a bracket to hold them in place route the rubber hoses off of each one to the driver's side fender to where underneath the fender on the face of the firewall you could pass the hoses into the engine bay and over to the washer pump. The design would have the tubes no longer attached to the cowl cover but attached to the steel undeneath of it. Just watch out that the wiper linkage does not rub against the rubber tubing and where it's routed.
Ypu may want to consider making the carb spacer out of a non heat conducting material to keep the carb cooler. Then you would have your spacer and a carb heat shield.
If you are custom making you're squirter lines you can use your choice of material(non corrosive - either aluminum or stainless steel). Weld the end closed and drill 1 or 2 very small holes in the end. Number 60 drill or in the range. It's tricky drilling with very small drills so use care not to snap them off. If you have the squirter mounted on the wiper then you can drill the side of the tube and have the fluid come out there instead of trying to put a 90 degree bend in the tube and losing the steathness look.
Think of it as you've honed your machining skills and have the process and tooling down pat. (LOL) When I'm not busy repairing machines at work, I end up making something for the car(out of scrap metal of course). I tell the guys I'm just honing my machining skills. I was machining fuel rails the other day for the 64 and the boss walked by. He said "how's the fule rail going?". He doesn't know what it was but someone mentioned what I was doing. He didn't care as long as all the plant's machines are going. He's from the floor and knows if everything's working then everythings OK.
I forgot about this post. I got them done. All I did was cut the tubes and mounted then under the cowl and ran the line inside the cowl. I circled the only tube seen. I did it like that so I didnt have to drill any holes just use a grommet in a hole that was already there..