Gauge and Horn help!

[Rustislighterthancarbonfibre]

While having the engine and gearbox done for my 13/60 ive taken up a family member's offer to make me a new dash!
ive been wanting to 'install' a electrical smiths tachometer on the left side of the 2 cut outs and put the speedo on the right.
ive found a nice MG smiths tachometer which is of simerlar design to the speedo -
http://www.ebay.co.uk/itm/Original-Smiths-Electric-Tachometer-RVC1410-00AF-MG-Midget-6-75-9-77-WORKS-/150773548784?pt=Vintage_Car_Truck_Parts_Accessories&hash=item231acdc6f0#ht_500wt_1361

just wondered if there would be any reason why this wouldnt fit? it looks to me to be the electrical type?

just wondering if anyone could suggest a better match of gauge with a chrome surround preferable someone uk based!

I've also got a Mountney  GT steering wheel and boss fitted to the car and need to know the correct pencil size as i cant seem to find this information anywhere?! i think theres 2 different sizes?

thanks Liam

[Goody]

Here is a pic of my Red Conv's dash.  The previous owner installed the tach, volt and temp guage.  I have since added a oil pressure guage to the left of the tach.

I beleive the tach is from a Spitfire.  Only problem is when the hole was cut for the tach due to room their is some of the orignal hole for the tem guage visiable.