The ICC report for LVLs provides the equivalent specific gravity to use for LVL bolt design. See Table #2 of the ICC report. The value is 0.5 which is the same as DF as mentioned above.
Typically, when I use steel thicker than 1/4", I still use the 1/4" values with the assumption that the steel thickness does not govern the capacity of the bolt if the thickness is greater than 1/4".
I agree with Phil1934, I would likely consider a steel beam in this situation. We use flitch beams, but generally only for vaulted conditions or situations that just barely exceed a wood beam. With this assembly, I'd feel more comfortable with a W10x steel beam section. I wouldn't think the cost would be significantly higher.