Im not sure how fast you? i do believe though, getting in some Med ball work, plyro’s etc will pay dividends to you sometime soon.
If you havent seen it yet, the GPP dvd has excellent hops, throws and plyro’s etc that at your strength levels in the gym, you could make some wicked running gains.
However, dont just drop the squats off and replace and also dont just Add in the above without looking in your program what you can take away (squat volume perhaps? 2-3 sets total perhaps?)
good luck in the 350m