

The tanks is Big Bertha. My great uncle was the gunner and is the gentleman standing on the left in the second photo. I'd no idea these photos existed until just the other day and now I'd like to pay a humble homage to him and his crew.
My problem is that I'm clueless about Shermans. I can tell you that it's a late HVSS 105 Howitzer tank of the 777th tank battalion of the 10th Armored Division. Beyond that, I can't discern much in the way of details.
I have Dragon's kit 6354 in the stash and I'd like to use it as a base. However, reading the reviews of it on PMMS make it sound nigh unbuildable, with the mantlet being the grossest offender.
My desire is to correct it as much as is practical. Kitbashing isn't really an option at the moment, and I'm not after 110% perfect detail. But, I would like to correct major, glaring mistakes. What do I need to do to this kit to get it to match Big Bertha in the photos? Does anyone have a tweak list or any other information for me on aftermarket correction parts, etc?
Thank you!