Job offer salary help

So im a computer engineering student in FL (USA), about 2 semesters to graduate... I got a co-op job as a Software Engineer, im working about 30 a week and making around $20 per hour..

When i stared here 2 month ago, they had a guy that was making i think 70k per year (but he was hired by one of those hiring agencies so he was making less because of that)

Now i was just asked if i wanted to get hired full time since they like what i do, and i match in the position, and fit in, etc

They basically asked me that i could either work full time, and go back as a co-op and probably pay me more as a co-op (30hours a week). I will take about 4 classes (3 and a lab) next semester, so i dont have a problem working 40h a week, and the rest of my degree is not that hard..

So my employer asked me how much do i want for a full time job, and how much do i want for a part time... Also asked me which way i wanted to go...

Now i have until monday to answer this question... But im thinking...

Full time 65k-70k (salary employee with benefits)
Part time $27/h (hourly employee no benefits)

So what do you guys think i should ask for Full time or part time if i decide to go that route