Yeah, you are right on the SS -- the $205K is the delta between what you'd otherwise get for full SS vs. what you'd get with less SS + pension. Sorry about that.
But I do think you need to consider the amount you are contributing to the pension, because that is an automatic deduction from your pay that you wouldn't have at another job. So one option would be to blow it on more stuff. But since you're living now without it, you'd likely just put that extra cash in some other investment, right? So the real value of the pension is in the company's contributions, and possibly the tax-deferred savings vehicle (if you have otherwise maxed out available tax-sheltered savings).
Example to illustrate: Say you make $50K now, and you put $18K toward your 401(k) and $5K toward your pension. So you are living on 50K-23K= $27K (gross -- ignoring taxes for simplicity). Meanwhile, assuming your employer adds $10K/yr to your pension, so the total contributions go up $15K/yr, and the pension earns whatever it earns, so that in XX years it will be worth YY. [Side note: you do not actually have to compute this out -- you already know that your pension will have a 'stache value of @$375K in 18 years. I am just breaking it out here as an illustration.]
Now you look at another job: same salary, but no pension. Now you can put away the same $18K to your 401(k), but not the $5K toward the pension, so you end up with $32K gross -- that's $5K extra left. One option is to give yourself a "raise" at the same salary and spend it on other stuff -- but that's not an apples to apples comparison, because now you have increased your lifestyle to $32K instead of $27K. So the other option is to open an IRA* and put that $5K/yr into VTSMX -- that is the apples to apples comparison, because your living expenses stay at $27K, and all you are doing is changing where you put that remaining $5K.
Now, that IRA will not get as much every year by way of contributions, because you are only putting in your own $5K, and not the employer's $10K. But since it is in VTSMX, it will probably grow faster than the pension, because pensions tend to be invested more conservatively. So you can calculate out what $5K/yr in VTSMX will likely be worth at whatever your target date is. FWIW, I just ran a quick online calculator, and it said $5K/yr in an IRA for 18 years is on the order of $180K (gross).
So for your case, the "value" of the pension is then the delta between scenario 1 above and scenario 2 here. Scenario 1 is $375K minus WEP = $205K. Scenario 2 is $180K. Therefore, the net "value" of the pension is on the order of $25K.
*I'm using an IRA in this example because that way we can keep focusing on gross numbers, because the pension and IRA are both pre-tax contributions that are taxed on withdrawal. Obviously, if you can't do a tIRA or have maxed out tax-sheltered options, it can get more complicated.