i think its better to be more conservative as ur engine internals are still stock. the harder u push it, the more u shorten the lifespan of the engine.
my personal opinion is...why not do up ur engine first (conrods, head studs, valve springs etc) and while u're at it... change the oil seals etc too. Once u've made ur engine relatively bulletproof, u can push it however hard u want and still have peace of mind.