I did this when I changed from Strombergs to SUs on my 164. You will have
to drill some holes so everything fits and maybe put some shields between the
carbs and the filter box, also on the front side because there may be holes
that cause it to leak. I suppose you could patch them with duct tape. I used
the heavy green file folder stock.

The center to center is the same but the other holes are different.

If you use HS6 carbs the old heat shield protects the float bowls.
If you use HIF6s you need the newer separate shields because the
old shield does NOT protect the float bowls. (Thanks, Matt!)

I just installed HIF6 carbs on my 122 and Matt sent me the separate
shields. Likewise I had to drill a lot of holes to get it to match
but the center to center distance was the same.

STRONG RECOMMENDATION: Be sure everything about the airbox is good and
TIGHT!! You don't want any hardware going into the engine and it can indeed
happen. (Ask me how I know....)

BTW I found some old oilpan bolts with integral washers and 7/16" hex that
work really well for holding the airbox onto the carbs. They are good and tight!

Have not piped cold air from the front but a flex pipe headed down might
work pretty good as long as it misses the generator and belt.
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma