International Exposure in Retirement Accounts

So currently, I utilize my post-tax 457b and my wife’s Roth IRA as a unified portfolio to keep costs down, as anything on my 457b, aside from VITSX, is more expensive than I’d like it to be. I have a 75/25 split between the 2 accounts, with the 75% side being US Markets (VITSX and FSKAX) and 25% being international (was FSPSX, just changed it to FTIHX). I have read that a 60/40 split is the approach that Vanguard follows, but I feel more comfortable having a bigger bias in the US Market. I lately considering moving from FSKAX/FTIHX in my wife’s account to just having VT, but I think that takes away far too much of my international exposure. Does anyone have an argument for what % my international exposure should be and why?