For me 1 will think of putting in L250 since K3 series engine won't suit the engine bay. Say afew Viva swap in L250 can perform really well even its a 660 cc engine...
really can't? even kancil can put CB or K3 engine what... admitted its a bit tight but its possible... even kelisa/kenari can pun K3 engine with some room to spare...
Stock L250 engine in Viva = Nice performance
Modded L250 engine in Viva = Great performance
K3 stock engine in Viva = You wanna fly aaa?