Been on one javelina hunt, 2008 West Texas, My Dad, son, and myself.
2 taken with a encore (Rifle) 250-3000 100 gr hornady (My Dad)
2 taken with M-7 Rem. 260 Rem. 120 Rem PSP CL (My Son)
1 taken with Contender (pistol/15") 7X30 Waters, 120 Hornady (Myself)
To do it all over again, I will, I would now consider, a 22 Hornet or a 223 Rem. or because the limit was 2, both.
I also shot an Oryx, in Africa, Tough animals to say the least, But, any deer caliber in the 270 and up with premium bullets would be my choice. I used a wildcat 300 mag. with ballistics similiar to win. 300. Your 35 Whelen would equal perfection also. Good luck
CRASH87