Outgoing Arlington School Superintendent Larry Cuban has a favorite fantasy.

"I always have this scenario where the County Board chairman would lean over his desk and say, 'I think this is one of the finest budgets the school superintendent has ever presented to the community,'"

Yesterday, as Cuban presented his final budget proposal, his hopes for such kudos were dashed. No sooner had he proposed a $59.8 million budget for fiscal 1982 -- one that would increase Arlington's education spending by 11.5 percent -- than he was attacked by the man he had hoped might praise him.

"On the surface, [the proposed budget] appears to be Dr. Cuban's parting shot at the County Board and the school system," complained County Board Chairman Stephen Detwiler. He called Cuban, who will leave office March 1, "irresponsible" for issuing a budget that calls for "at least twice the [percentage] increase" that the County Board had indicated it will approve.

Cuban's proposed budget, which must be approved by the school and funded by the County Board, depends on a nearly 15 percent increase in county revenues -- a point that is sure to spark more wrangling between the school board and the County Board over higher school spending in an era of declining enrollments.

Earlier in budget deliberations, the County Board issued "guidelines" to the school board, limiting its spending increase to 7 percent and setting the county's contribution to schools at $43.5 million, well below the $8.6 million that Cuban proposed.

Cuban, leaving to begin a research project in March, proposed giving teachers 10 percent pay raises and doubling their longevity pay. His budget proposal calls for no new major programs.