Is it possible to drive TTL inputs from 3.3v microcontroller

The datasheets should tell you the minimum voltage required to register as a digital high for your receiver, and the minimum voltage guaranteed at the output for a high from your sender. Just make sure they're within each other's limits.

A TTL input signal is defined as "low" when between 0 V and 0.8 V with respect to the ground terminal, and "high" when between 2.2 V and 5 V (precise logic levels vary slightly between sub-types). TTL outputs are typically restricted to narrower limits of between 0 V and 0.4 V for a "low" and between 2.6 V and 5 V for a "high", providing 0.4V of noise immunity.

http://en.wikipedia.org/wiki/Transistor-transistor_logic#Interfacing_problems

"is it ok to assume"

your number of assumptions should be inversely proportional to the amount of money invested in your work. I am not sure how much is in this project but I always try to keep that in mind.

As for the device: are you reading, writing or both? If reading, should be ok since you said your device is 5V tolerant. If you are writing then I would still stick with some sort of level shifter like this. You really can't know what will happen if you use a device out of spec (could get lucky but you could also get really really unlucky).

I have used one of the level converters and they work great!

Pericom AN66 is a useful application note on logic family interfacing. It covers driving TTL from 3.3V CMOS.