Hello everyone!

I had a question about the ratio between the Bench/Squat/Deadlift 1RMs. I've read somewhere (possibly here) that the proper ratio for the three powerlifts (at least for beginner-intermediate weight lifters) is 1:1.5:2, or that the deadlift should be twice as much as the bench, with the squat falling directly in between the two.

I'm looking to join the US SEALs in the distant future, so while heavy weight strength training is far from a priority, it would be a great perk while getting to graduation and I've been using the ratio as an estimated goal guide for maintaining a balance in my body; nothing serious.

It is, however, very important for me not pack more weight/space on my body than would get in the way such that I can assist my teammates as best as the situation requires without getting in the way.

So here's the status: for a SEAL, strength-wise, upper body is most important. Therefore, my baseline lift is the bench; it guides the other two exercises for me. Squatting comes next as leg strength is also important in carrying large weights, but isn't as vital since legs that are too large will impede my running ability. And least important, possibly to the point of negligibility, is the deadlift, as the areas it covers majorly are least important in the SEAL environment.

Here's where I stand for 1RMs (lbs.):
Bench: 255-265 (with a maximum goal of 315-335)
Squat: 435 (with a maximum goal of 455)
Deadlift: 385

So finally, here's my question. I mainly do deadlifts in order to maintain the lower back strength needed to have safe stability while doing heavy squats. I really don't want to increase much farther than I have to, but I'd like to know: What is the minimum deadlift 1RM I need to have safe and stable squats (as far as my back/spine is concerned). It can't really be 606 lbs. like the ratio says, right?

Some other info for your consideration if needed:
Height: 6'2"
Weight: 230 lbs.
Strength training days/week: 4
Military-style workout days/week: 4-5

Thanks to anyone who can help!