Transferring Equity Investment From Solo401K into Roth

[Todd Magin]

How do I determine the value for tax purposes of an equity investment when transferring ownership from a Solo401K to a Roth account?  If I invest $100K in an equity deal (syndicated or crowdfunded) using my Solo401K and later (ie in year 4 of a 5 year investment) decide to transfer that investment into a Roth account, do I simply use the "face value" of the investment ($100K) or do I need to apply interest to the account (even though returns are not guaranteed).  If so, how is that interest rate determined, since there is no way of knowing what the actual return will be?