Don't make your ST more than 5, as you could take the ST implant and then the Weapon Handling perk at lvl 16. This is probably around the time you'll find an AMR anyways. I always find that my sniper builds work best when I ignore VATS completely. This frees up a ton of perk slots, since a lot of the guns combat perks are VATS based. You can also work with a lower AG, since you won't have to worry about APs. An EN of 7 is *nice* to have, since you can take most of the implants. You may wish to make sure you meet the requirements for the Cowboy Perk, since using the Trail Carbine with that perk is one of themost effective sniper builds in the game, even though I myself think it's a bit redonkulous. Get Boone and Ed-e, especially Ed-e, and you don't have to worry about a high PER. How about:
Before Implants:
ST 5
PE 5
EN 7
CH 3
IN 6
AG 5
LU 9
After Implants:
ST 6
PE 6
EN 7
CH 4
IN 7
AG 6
LU 10
Take all the non-vats damage perks and all the +crit perks you can stomach. Pump guns, sneak and repair (or melee for a cowboy perk build). Kill away.
-Gunny out.
As a Sniper you are presumably getting nothing but sneak-crits, in which case a high LCK is irrelevant. Assuming that's the idea, then you might try something like this:
Pre-ImplantsSTR: 5
PER:6
END:7
CHA:3
INT:8
AGI:5 (6 w/Small Frame trait)
LCK:6
Post-ImplantsSTR: 6
PER: 7
END: 8
CHA: 4
INT: 8
AGI: 6 (7 w/Small Frame)
LCK: 7
with the Dermal implant for added DT.
STR 6 + Weapon Handling perk means you can use the AMR with no penalties from L16 on, assuming Guns is already at 100 (which it should be). With the Dermal implant you can stick with Light armor and choose perks accordingly to make it easier to relocate if discovered, since you shouldn't be hit often enough for the lower DT to be problematic and staying with Light armor will aid in sneaking.
The difference in skill points between an 8 INT and a 9 INT is at most 17 SP, which isn't going to matter as sometime in the 20s you will be padding out secondary skills, if not before then, so there is no need to raise INT with an implant. LCK increases add a point to all skills at each odd number because the equation rounds up, so starting with an even number means the implant isn't 'wasted'.
That said, if going for a 'pure crit' build you could drop two points from END, start LCK at 8, and forgo an END implant, or even shave a point from AGI and start LCK at 9, although that 1% is rarely going to matter. You want an AGI of 6 post-implant regardless for perk reasons, so plan accordingly.
If you're going to use a Trail Carbine you may want to invest in the Cowboy perk; it has a co-requirement of 45 Melee, which may be more than you want to spend early on in a skill you likely won't use much, if at all, so that should be taken into consideration. On the other hand there's something to be said for carrying a Combat Knife as an emergency backup, so YMMV.