help me pick my 401k funds

[frugalnacho]

new 401k plan at work and I need to pick my funds.  Our IPS is 100% stocks, 60/40 VTSAX/VTIAX, or if those funds aren't available, the closest I can replicate them.

Fund options with reasonable ER:

FUSVX - fidelity 500 index fund - 0.05%
FSEVX - fidelity extended market index fund - 0.07%
FSIVX - fidelity international index fund - 0.08%
FSSVX - fidelity small cap index fund - 0.07%

My 401k plan has automatic re-balancing so I could go 60/40 in my 401k for simplicity, and then only have to rebalance our IRAs and taxable accounts to 60/40.  However we currently have about $240k invested with vanguard, so I can go 100% domestic, or 100% international in my 401k and still maintain my desired AA, probably until FIRE.

How would I best replicate VTSAX or VTIAX? 

[etselec]

80% FUSVX and 20% FSEVX should approximate VTSAX fairly well. International is harder — FSIVX doesn't have Canada or emerging markets, so it doesn't approximate VTIAX quite as well. 

If it works with your overall mix of assets, I'd say:

• New 401k: all domestic (use auto rebalancing to keep your 80/20 ratio of FUSVX/FSEVX)
• IRAs: mix of domestic & international as needed for your AA
• Taxable: all international (or as much as possible — obviously stick to your overall AA, and keep any existing domestic here if selling it would trigger a ton of taxes)

Having more international in taxable means you'll get more foreign tax credit. Not a huge deal, but a nice bonus if you can swing it.