High Torque Gear Reduction Starter Motor

[Geoff Kingston]

The starter motor on my 603E appears to be on the way out, standard replacements do not seem that expensive but for about 50 to 70% more several suppliers offer High Torque Gear Reduction Starters which from what I have read spin the engine faster giving better stating and use less power.
I see on a few sites however mention is made in some applications of clearance issues with the sump and exhaust manifolds and with the engine in a Bristol the chassis as well?
So a few question has anyone fitted this type of starter motor to a 318 engine in a 603 were there any clearance or other issues.
Were the benefits worth it and if so what was the make and part or model number of the unit and who supplied it.
Any help and advice will be much appreciated.