Hi,
I work as graphic designer in printing house and I have experience with T shirt design.
I have a few questions about image. If you will use silk print process, do I have any color restrictions? Another my remark is about resolution. If we print high quality magazines with 300 ppi resolution, I don't understand why you need 350 ppi? I can deliver any bitmap resolution you want, but I prefer to draw in Adobe illustrator and deliver resolution independent file. It is much better choice if you want to change anything in image in time.
Feel free to contact me.
Best regards,
Zoran