Export synonyms content to tables
I think the most efficient way in your case will be:

--uncomment if you are allowed do this: drop table HUGE_TABLE;
--uncomment if you are allowed do this: drop table HUGE_TABLE_WITH_BLOBS;
create table HUGE_TABLE NOLOGGING PARALLEL 4 as select * from HUGE_TABLE@Distantdb;
create table HUGE_TABLE_WITH_BLOBS NOLOGGING PARALLEL 4 as select * from HUGE_TABLE_WITH_BLOBS@Distantdb;


You can omit: "NOLOGGING PARALLEL 4" if normal mode will be enough fast.
Remember about creating constraint and indexes on newly created tables, default only  NOT NULL constraints will be copied.