Hi Sven,
This is the first time I've ever seen the original plan that has #18 as a dogleg. My guess is that 17 became a long par three around the same time. The original 17 must have been quite a rugged hole, as the land continues uphill quite a bit behind the current green.
Looks like #2 was 446 on the Plan above...today that hole is a par five at 520ish. Looks like all the other holes are similar length, although #8 is now 440+, #10 today is more like 470 (and plays straight-on with no slight bend), and #15 is around 500.
Charles River has always been wishy-washy about par, as the tournament card always plays to a par 70 with #7 and #10 as par fours where they are par 5s on the member card. The lengths of the holes make sense to do this, but 7/10 both have dynamic greens that make way more sense at the end of a par five.