Adding new track to pre-existing recording

[Doombeard]

Heya everyone,

Me and my buddy are trying to create a guitar track to replace a vocal track (we have the track both in vocal and instrumental form), but I'm having difficulties making the guitar blend properly with the rest of the song. Unfortunately we're in a situation where we don't have access to original stems, so the instrumental is the best we got. Perhaps a bit of an unusual case, currently trying to play around with some mixing, anyone here that may have experience or ideas?

Thanks in advance!

[Garpocalypse]

Assuming it's as good of a performance as you can get,99% of the time it's the track you are paying the most attention to being too loud. Start with it being below the level of the instrumental to where it you can barely hear it then tick it up a few db at a time until it sounds right. you'll want to look up typical EQ cuts for guitars and start from there to shave off unwanted sound. A little delay and reverb will help too and then see if you can get away with a little more over the master to help it blend further.  Just to be clear we're talking nigh inaudible levels of blending reverb as a final step but if can get everything else tight you may not even need it.  

Depending on where the vocals were you may want to make a slight dip in the instrumental with an EQ in the upper mids to make some room for whatever freqs your guitar is hot in. (to find it look at the peaks on a frequency analyzer on your guitar track) Dip it on the instrumental -3 db but certainly no more than 5 and that little nudge should help.  

[Doombeard]

Cooool, I just got back from work so time to tinker a bit. Thanks so much for the help/input!