[wensum]

I have a Daimler SP250 which runs on two 1 3/4" SU's, (2.5 litres) a 3 Litre Lancia Lambda on a single 1 3/4" SU and a Vauxhall 30/98 on two 1 3/4" SU's (4.25 litres)
I think the SU's you are thinking of using might prove too small?
Keith