Can I retrofit fuel pump on type 44 with 43mm one?

[kbogach]

My 200tqa has older 3 legs support system,  info on Chris Miller's site 
does not apply in this case, I believe.  So far, I replaced mine with 
used one from junk yard twice.  All three were humming.   Could it be 
that  the problem is somewhere else?  All pressures tests are fine 
though.   Anyway,  it would be nice to retrofit smaller pump - it cost 
less and quieter.

Thanks in advance,
Konstantine