Hi,
dunno about the voltages (don't feel like measuring them, sorry) but i did use a 74HC14 and have lpt: set to ecp/epp.
I believe some people using older AMD processors in their pc's have troubles getting flasher to work? Not sure about what processors give troubles... you might want to search old posts on this subject.
oh... One more thing.. use flash software with win98... if you want to use dos you need to use a dos extender like CWSDPMI.EXE
and if you use win2k and I guess also with xp you need to use UserPort.exe to get direct acces to lpt port.
Goodluck!
-=K=-