If you want proper baseball games, you want pitch and bat, not pinball machines, as there only a handful that are marginally interesting to most people under the age of 14.
Your grandsons will not be disappointed with pitch and bats, children are always amazed.

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In priority order:

1 ) Deluxe Official Baseball (WMS, 1960)
2 ) 1962 World Series (WMS, 1962)
3 ) Pinch-Hitter (WMS, 1959)
4 ) 4 Bagger Deluxe (WMS, 1956)
5 ) SlugFest! (WMS, 1991 and the 1993 reissue) <---Only SS on this list

These are correct examples at the top of this genre list, not considering other great examples from Chicago Coin and United.
Proper restored examples are worth very good money, and last forever, if maintained.

If you want to go "brand new", get on the waiting the third production list for the additional run of Zombie League All Stars (Gizmo Game Design, 2017).
The first two runs are already sold out, as people underestimated the retro nostalgic features, keeping in mind this is no comparison to the "sherman tank" EM variety.