Hi Richie,
Good fuel tank and engine bay hose supply source reference from texasz.
Engine Bay Fuel Lines:
From w3wilkes in 2017: I just did all my fuel lines this year with Gates E85 rated hose.
1/4" fuel rail to carbs - maybe 2 1/2 feet
5/16" supply side to fuel rail & tank to steel line - about 6 feet
3/16" return line from rail to steel line & steel line to tank - about 5 feet. These all seemed to fit perfectly.
Note: The 3/16” and 5/16” tank to steel line hoses listed by w3wilkes are already included in your metric-sized JBugs “shopping list”. Since the minimum purchase is 10 feet, you will have plenty for the engine bay.
You can purchase 1/4” or 6mm cloth wrapped fuel line on eBay:
https://www.ebay.com/itm/192199329085?hash=item2cbff9053d:g:i4UAAOSwcgNZKeUY&amdata=enc%3AAQAHAAAAsBAXKMKvoUlGz0Yf%2BSGYq1PML9tMxpmL%2B8LpNFHrvaRIJmgfLtH5SgTKv%2BFmVmNATItn8YxtYgMfAxrOGrVSUlqtYBCyYTVCW9UmXZHRBt8Vg%2BTyiUjStYub8iSxa6pAg8g4lRI2aIwBbRiXZ0W2ZWJAPO%2FFxkWNQWVDnNrIuAoRWlCgoBnlR54tz3VjQ0T24Ow4EIddBFX3meil4evwEsCkhGHEsf%2FbZf%2BcMW%2FXnF7N%7Ctkp%3ABk9SR8TW4cjQYQ
Air Bubbles:
My mistake, never thought about air bubbles from the tank/supply side. If you are seeing air bubbles coming out the bottom of the filter while the engine is running, you are taking the right steps starting from the fuel source (tank) by replacing the tank hoses and working forward to the engine.
When the tank removed is removed, see if you can get a vacuum pressure reading from the fuel hard line in the rear of the car to the hard line output in the engine bay. It would be a good way to test the spliced connection and see if there is a small hole in the hard line you cannot see.
Harbor Freight sells a simple, Brake Bleeder and Vacuum Pump Kit for $25. You can find similar kits on eBay. It never worked for me as a brake bleeder, but the vacuum pump is useful. Alternatively, maybe you can borrow one from a friend.
Wear eye protection.
Blow out the hard line so the vacuum does not intake fuel or dirt.
Plug the rear section (phillips screwdriver in old rubber input hose) and put a gauged vacuum pump on the rubber hose going into the fuel filter input.
Pump up the vacuum and see if it holds. Not sure how much pressure you should apply, maybe 10 or 20 psi and let it sit for a while. Would assume you would see a pressure change fairly quickly.
If it leaks, you have identified the leak is between the two ends.
It could be a leak at the splice or in some other location in the line. I read that the steel lines pit over time and leak. I believe the replacements are stainless steel.
Check your build date to purchase the correct line.
If the hard line tests okay, you could place a heat wrap around the short rubber hose section and leave it be. Use metal or regular zip ties to hold in place. I have heat wrap on my speedometer cable so it does not melt from the headers.
I missed a question from your initial post:
Your question: Adapters anywhere other than the one on the replacement fuel filler neck in light blue?
Answer: No additional adapters that I can remember. The referenced “light blue” adapter in my Z used to connect a vent hose to the fuel filler was made of thin, crushable plastic (junk). I replaced it with a hardware store hose connector. I just carried the fuel filler neck into the store and tested connectors until something fit well. You can also purchase a connector from ZCarDepot for $12. If I remember correctly, the connection is only press fit. No need for a hose clamp.
Hope your project goes well.
Nate