I want to buy a Steez A for deep cranking but I am stuck between the 5.3 and 6.3 gear ratio. I’ll be using cranks as large as the 
Big M 7.0. 

I would like more IPT than the 22” the 5.3 offers but I am concerned about cranking power if I go with the 6.3. I would like to hear everyone’s general thoughts about this. I would also like to hear if anyone has used the 6.3 Steez A for big deep cranks.

Too small of a spool for long bombing casts in my opinion.

2 hours ago, Columbia Craw said:

Too small of a spool for long bombing casts in my opinion.

It should be okay using 10lb line I'd think

   The OP specified the Big M 7.0. I didn't know there was a 7.0. Perhaps he means Big M 7.5? That lure is over 2 ounces. I doubt that 10 lb. line would be the best choice for a lure that weighs over 2 ounces, especially on a "long bombing cast". A person has to take into consideration the effects of abrasion, and any weaknesses in the line, too.       jj

I wouldn't think so.  I have the Steez SV TWS and it is a different reel than than one you asked but I didn't like it for deep cranks.  It tends to flex a little when under load and with deep cranks.  It just felt weird.  If the A is anything like that I would pass especially on something that is 2+oz. 

 

My personal preference for deep cranks is either a Shimano Antares 12 or a Shimano Calcutta.  You would think you would need something more stoat for such a big lure. 

Any 6.3 will be fine for deep cranks. I typically use 5.3 for the big deep stuff just because I feel like I get more bites. I use 6.3 for shallower cranks. I have thrown mag deep cranks on 7.3 before and caught fish and had no problems.