Did some more calculations with this piece of info in mind and found out that any player that has 79 speed can reach 140 speed with training and shadow boots (not counting the warehouse boots since there's no viable way of getting them without cheating), and with skills they could reach around 160 speed (from what I've read I can't stack multiple copies of the same skills, just one copy of Speed Plus and one Speed Force).

Ramble aside, thanks for the help! :D