mk1 AGU fueling options

I've read all sorts of options for fueling a mk1 1.8T (AGU) transplant but I'm wondering about this …

This guy welds a mk4 pump/sender flange to the mk1 fuel tank so he can use the mk4 fuel pump/sender (the assembly includes a surge tank that surrounds the pump).
https://www.youtube.com/watch?v=oV7YqVctQ60.

The tank flange is from https://www.sdg.industries/store/p/mk4-weld-fuel-pump-flange. Also available is a fuel level signal converter so you can use the mk1 dials (I guess to shift the signal to the correct ohm range).

I have the complete, running mk4 GTI as a donor and I was going to pull the mk1 tank anyway …so this seems simple. As the mk1 is carb, this option avoids the surge tank (or replacement tank), lift pump and external pump.

I've not seen anyone else do this but a commercially available flange suggests it's common. I imagine I would just swap the mk4 in-tank pump for a higher capacity pump and bigger fuel lines so I'm prepared for 240HP (if I opt for that).

Am I misunderstanding something? Why is this not more popular?

see:
Amazon

For me looks like a lot of extra work i just dont need. I have a gti tintop with external high pressure fuel pump which i feel will do....

Thanks Briano. Perhaps I misunderstand, but I understand the usual options are:

• a lift pump, a surge tank and the GTI CIS high pressure pump
• a GTI tank (that includes swirl pot), a lift pump and a GTI CIS high pressure pump

 If I understand the product in your link, this is a CIS high pressure pump that replaces the lift pump usually under the sender. But this option has no surge tank / swirl pot and my mk1 is carb so it has no in-built surge/swirl.
The mk4 assembly has a pump that sits inside what looks like a cheap-and-cheerful swirl pot. All I'd have to do is buy the flange and have it welded to the tank - tank's coming out, anyway. This option still seems simple and it's easy to upgrade the standard pump if I want 240hp (I understand the standard pump is marginal). I've not seen this written up anywhere so I'm wondering if there's something I'm not understanding  

Over on this side of the pond on the 84.5 and up Cabriolet's we had the External filter (swirl pot) that used the internal low pressure pump rated at 45 psi 33 gph,  to fill the filter and an external pump after the the filter that was either another low pressure pump rated at 45psi for the Digifant 90's with the 89 and under used the higher pressure 75 psi pump and banjo fittings every where.  While both had the same 13 gallon tank no internal swirl.  The earlier 84.5 and under used only the Higher pressure pump for the CIS systems.

I linked the Amazon page to show that a company was making OEM like Tank Sender/internal pump assemblies.

If you go with a higher rated internal pump and a in-tank swirl, that would have to use Fuel injection clamps instead of Jubilee clamps as the higher pressures for an external high pressure  may blow apart either the hose connections or the external swirl pot/connections.

On some of the non VW fuel systems tha I have worked on in Van's, Toyota's, Nissan's and Honda's the in-tank pumps were surrounded by a larger plastic case that acted like an internal swirl pot.   The difference was the
size of the hole for mounting it.  

I can't imagine a 200hp engine in the MK1.  Quick off the start.  

I am used to the 1.5 Diesel bunny and my 90-93 Cabbies that were 105 HP, with Manual and Automatics.  

I would regularly beat a Honda off the Start in my 90.  I had a higher rated Clutch and well a short shift kit and Header on it.  

As I am a little bothered by the after effect of a stroke, I enjoyed my Auto Tranny's as no clutching roll back on start on the hills of Georgia and the Atlanta Metro area, but flat out my occasional forays of 80-90-and 100 mph cruising on the interstates crossing America.  What I really missed in all of this was the 45-50mpg of the Diesel or the 39mpg of my 90 5 spd.  The mose I ever got was about 26mpg on my Autos with no ac on during the winter months of cross country driving.

Good Luck on your Adventure.