Triumph Repair: Matching speedo with 4.11 diff on rebuilt spitfire, angle bracket, speedo

Question
Hi

I now have my '65 spit fitted with a 4.11 ratio Diff, a J-type O/D and larger wheels. My current speedo (which I don't have the TPM handy right now), reads some ~40% over actual speed - when I am being paced at 60, it reads 90 or thereabouts. I realize that the larger wheel and tire size will also factor into this, but can I get some guidance to what years of Spitfire speedo will get me more in range with my 4.11 Diff? Right now I have the screw-on cable attached to the angle bracket on the tranny, so I'd prefer to find a screw-on replacement from a later spit - but I am lost in what I need to search for.

Thanks!

Answer
Hi Nick,
Go to this web site and follow the directions and e-mail the info along with the brand of speedo and possibly the number on the face of the speedo to these people to see if they can help. A friend who has several Triumphs has used these people and with good results even though they don't say "Triumph" on their web site.

http://www.paspeedo.com/ratio.htm

Howard