Alan, you really do pick 'em.

Pi wouldn't be pi then, would it?

There's a lot more to pi than the simple ratio of circumference to diameter of a circle. If we lived on a very small globe and were actually drawing circles on the surface then the ratio wouldn't be pi. But pi would still be pi.

Pi comes from Maths - along with a load of other transcendental numbers. It's a constant which comes out of many integrals. It's not really a 'Universal Constant' like G, h or k. It's a product of Maths and can't be 'measured' as such. Whatever geometry your 'space' had, you would still get pi from the Maths.