Timing cover and front seal replacement

["Simon Matthews" <simon_atwork@hotmail.com>]

I really need to replace the front seal on my '57 MGA's engine. I have a 
timing cover and seal from an early MGB ready to use as replacements.

I have never done this, and it doeas not seem to be documented in either 
manuals (Haynes or factory). What tricks/difficulties are there to this 
procedure?

I am thinking about renting a compressor, etc to remove the nut holding the 
pulley on -- what size socket will I need?

Simon