[TR] TR6 valve size question

[Tony Gordon]

After a long time away from TR'ing ... I am intent on doing an engine 
rebuild.  I am hoping to start with the head, and then onwards to the block. 
Once rebuilt, I plan to reintall the PI system that was installed in 2001 on 
a very tired engine that worked well but for the lack of vacuum at low revs 
(lesson 1: don't install PI unless you can crank 150psi in all cylinders). 
If anyone is interested, I can share my earlier notes on a PI retrofit (just 
email me off list for a PDF).

I hope to move up from the 72 standard cam to a Piper stage 2 road cam (well 
liked by PI folks apparently, but advice welcomed), with double 3-1 header 
leading to the 72 double pipes.  The car already has O/D, aluminum flywheel, 
and suspension mods aplenty.

I have a 72/73 head ... as standard it came with 1.44" inlets and 1.25" 
exhaust valves ... I have seen ads for larger inlets (and exhaust) valves 
... what is the perceived wisdom on the valve size?  1.50" inlets and 1.30" 
exhausts seem to be available ... the head clearance is pretty tight so I'm 
not sure what works.  Any advice?

Tony Gordon
72 TR6