That said, it's going to be some kind of crazy tuned turbo A-series that will put out more torque than the box can handle - as standard they put out 85 lbft and the 1850 manages 105 lbft stock, which is quite a big difference Assuming the gearbox is the same on the 1850 and Sprint (anyone?) you've got 122 lbft safely. Even if you've made a few mods to the engine it's likely that a lot of horses have escaped over the years.
If it becomes a problem you could fish around for a Stag autobox - same model, same bolt pattern at the engine end but will be safe for 167 lbft, since that's what the engine puts out on one of those when it works.
A word of warning though - if you're using it, the Marina uses the Dolly back axle too, which won't be too happy with the torque - especially in "enthusiastic" driving.