Instrument input Vs Mic input

Hi,
This is the original input stage of a mic preamp (Ampex 351) (click to make the picture bigger):


I modified it following this simpler one (only the black writings):


Now, beside the mic in, I want to have an instrument input such as a guitar. The red writings is what I think I should do for this. But I would like your opinion on a few of things:
1) do I need to cut the circuit after C1 and R8 or can I just let them in the path ?
2) if no, even though the input transformer would not be of any use, do I need to connect 8 and 4 pins together as in the original schematics ?
3) is that 82k a good value ?

Thanks for your input and sorry about my lack of knowledge.
Alex

[quote author="alexidoia"].....1) do I need to cut the circuit after C1 and R8....[/quote]

Yes.
Look at Gyraf's G9 input circuitry.

Regards,
Milan