trany problem

[razvan_ro]

hi all. i recently bought a 1988 s13 with a '94 ca18det engine. the original trany didn't get into 2'nd so i changed it with a ka24e trany... the thing is, that now, it shifts fine, but when i take it it into high revs, and upshift, it wont get into gear, unless, i wait a whyle, so the revs go down a bit. this my first nissan experience so, i do not know what could be the problem. the gear oil is a 80w-90...could this be the problem?..please help....