"By the book" you should have at least 50% BTC. You have that. Good.
The riskier the rest of the portfolio is, the more % should be BTC, but LTC and ETH should not be that risky.
Although it's not how my portfolio would (actually does) look like, but as long as you did your homework on which coin has what potential to rise (or not fall), you should be "fine".
(Just a reminder, don't invest more than you afford to lose, else you'll be very stressed when the market will have bad times and you may do stupid moves.)