In Japaense transistor numbering conventions
2SA1015 [ SA ] - PNP HF transistor
2SC945 [ SC ] - NPN HF transistor

In european naming conventions such as BC547,BF494 etc
B - Indiacates its Si device
C - Indicates Audio Freq Small Signal
F - Indicate HF.

Is it OK to substitute the transistor's with following
2SC945 ---> BF494