which gear ratio
 

I'm going to be putting a richmond 6 speed into my maro. I'm going with the nice low 4.22:1 first gear. I'm thinking of using a very high 2.80:1 in the rear for great low rpms in 5th or 6th. Performance wise, will the low first gear be good enough, or should I lower the rear gear a bit? I'm also concerned about the strength of a 2.80 gear since it's pretty thin. It's a 9" ford gear though.

It will depend on intended use and the size of the tires. Will you be using a 26-28" tire, and will you have enough power to push it all in top gear?

They do make a 3.00 gear for the 9" that is pretty tough.

What is your 5th and 6th gear ratios? It would seem that a .6 6th gear would be nearly unusable with a 2:88 rear.