LSx motor mount question

[6D8_C10]

Ok, I am going to put a 5.3L in my truck. I was doing a little research on a few sites about the install. I was just reading an article in Classic Trucks where a guy was putting in an 5.3L in his '72. He talked about having an issue with the motor mounts. He said his original 350 was in the 1st two mount holes (closest to the firewall) and the distributor was too close to the firewall. He said that most other c10 that he saw had them in the last 2 holes closest to the radiator.

So, I went out to look at my set up, and my motor mounts were also in the 1st or most rear 2 holes closest to the firewall. Yes, my distibutor is right up against the firewall.

So, will I have issues with putting in my 5.3L?
Do I have to move the 5.3L forward?
If I do have to move it forward, that means I would have to move the transmission forward (for th350 trans) and lenghthen the drive shaft.
Or, if I put in the 4L60e I will not have to lengthen the driveshaft just move the trans mount?