Mmh, I got no details on that upgrade kit. But just to
compare prices:

H1 5x7 High Beams Hella           57.50 DM =  35.00 USD
H1 5x7 High Beams Bosch           63.00 DM =  38.00 USD
H4 5x7 Dual Beams Hella           57.50 DM =  35.00 USD
DE 5x7 Low Beams  Bosch          135.00 DM =  81.00 USD
DE 5x7 Foglights  Bosch          245.00 DM = 147.00 USD

Today I checked the sizes, if the 5x7 will fit into the
Vanagon framework and rectangular grille. The Bosch DE
will fit into the outer corners, as the H1 will fit into
the inner position to replace the standard H1 high beams.
About a half to one inch have to be cut at the inner edges
of the square headlights grille. But there are still
a one inch gap in top and bottom of the 5x7 headlights,
which could be closed by a modified Audi 5000 headlight
mask.

I don't think, that replacing the standard DOT square
headlights against the 5x7 H4 will improve the lights
more than replacing against the standard Vanagon H4
squares, which are bigger. The Vanagon standard H4s you
will get for a price of 192.00 DM (115.00 USD) each. No
modifications or new brackets are needed in this case.

Regards
Helmut
'80 Vanagaudi