riojin: before I say anything what engines have you had experince with first hand in th ecar that made you feel like it lacked low down torque?

not for show: If F1 engines used wider angles the head would be a little wider yes but it would also be quite lower because the inlets wouldn't be so long anymore. I dont think it would add any extra weight also.

As for the valves:

4age

inlet: 29.5mm
ex: 25.5


4/7afe

inlet: 31mm!!
ex 24.5mm

also the well known Bill sherwood is also building up one of these engines and he has fitted 33mm inlets I think by memory. Looking at the chamber theres stacks of free space ofr bigger valves. How much material you can take away from the inlets to have the right cross sectional area is another story.. However there is enough to suit 33mm valves so that should be enough for anyone.