I am not sure how far TTL would travel. I would guess that it is much shorter than using a max232, since you don't have the range of voltage available. You could test it without...., or you could put a max232 on both sides, or...
You might be able to get by using a max232 on your hardware side, and on the serial lcd side, use a resistor as shown in the PBP manual under SERIN example. This 22k resistor would protect your serial lcd (RX) from the max232 voltages, but should preserve the distance, since the +/- voltage is getting all the way to the resistor.
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