I wouldn't do it that way! Just take the old hose off, (try to keep it in one piece) take it to your local carburetor specialist (or engine rebuilder) tell them what it came off and where abouts (ie fuel tank) and buy a short length of matching hose. (You do need the right hose or it will give you issues.)

From memory it is reinforced hose, not just standard fuel line. The old stuff was also ribbed reinforced, but the modern equivalent may not be ribbed. If it comes anywhere near 27 bucks I'd try the next shop!!! But then again good hose is not as avail as it once was. If you use cheap/ substandard hose it will most likely either collapse, or split again within a short time. Get your carby shop to get you the hose, or recommend an engine shop. Ahhh I dunno about 50mm - cant remember, maybe 3/16ths ?

Not bad idea to be pretty choosey about fuel hose you fit to a place you cant see. I made that mistake once using cheap(er) fuel line to the separator on my HJ wagon, it split in 18 months, but I still thought it was new, the small air leak that arrived was enough to just mess with me for ages, made the car confusingly unreliable, and caused me heaps of crap, till one warm day I finally smelt the fuel vapour, checked it and the "new" hose was perished.